Latest / The Refrigeration Mentor Podcast / Episode 193. Designing CO2 Supermarket Refrigeration Systems: Applying Heat Recovery with Chris Griffiths of Omega Solutions (Part 3 of 5)

Transcript

Episode 193. Designing CO2 Supermarket Refrigeration Systems: Applying Heat Recovery with Chris Griffiths of Omega Solutions (Part 3 of 5) · The Refrigeration Mentor Podcast

• 0:00
  With CO2 as well, it has its own distinct advantages over previous working fluids that were in refrigerants. viscosity, it flows around the system very well indeed. It has high thermal conductivity refrigerants, so you get that good heat transfer in smaller pipes. Better efficiency in heat exchangers.
• 0:01
  And, almost is considered negative sometimes. temperatures, that larger Delta T is going to benefit us. We're going to get more heat transfer using that same fluid.
• 0:02
  Welcome
• 0:03
  to the Refrigeration Mentor Podcast. I'm your host, Trevor
• 0:04
  Matthews.
• 0:05
  As a former technician turned entrepreneur,
• 0:06
  my goal is to really help train you, educate you, and mentor you in the commercial refrigeration industry.
• 0:07
  Each week, I'm going to have top guests from technicians, Manufacturers to experts around the world to really help us grow
• 0:08
  and learn together by sharing their knowledge in commercial refrigeration, commercial HVAC, and not only on
• 0:09
  the technical side, but really the professional and the personal development side as well.
• 0:10
  I'm really excited that you're here. Now let's get a conversation going.
• 0:11
  Hey, I want to take a minute to talk about the upcoming refrigeration mentor learning programs. Every couple of months,
• 0:12
  we continue to roll out live instructor led sessions
• 0:13
  by subject matter experts on compressors, supermarket refrigeration, and CO2
• 0:14
  refrigeration.
• 0:15
  We're really here
• 0:16
  to help you grow. Get to that next level. Head to the Refrigeration Mentor webpage, refrigerationmentor. com. Check out the events page. There's a compressor masterclass, there's a supermarket refrigeration program, and there's a CO2 program. There's also free trainings, free
• 0:17
  workshops.
• 0:18
  Really, check them out. See if this interests you.
• 0:19
  Read a little bit about it because we're really here to help you. These live sessions are for you to come and ask questions, to learn a little bit, to grow. We've trained thousands of technicians from technicians from three to four to five years in industry all the way up from 20 to 30 years in industry.
• 0:20
  Either get them to the next level or get
• 0:21
  them back on track, build that confidence, that knowledge and that
• 0:22
  skill set. We'd love to see you there. We'd love to have you. Now let's get a conversation going. Welcome everyone to another CO2 Monday. This is week three of the five part CO2 refrigeration design series here.
• 0:23
  Once again, with my good friend, Chris Griffiths, and we're going to be talking about applying heat recovery to CO2 systems, and this is super important. You want to understand how to maximize. Your customer system by looking at the design. Do they need heat recovery? Is it going to benefit the most is the complexity of heat recovery going to be an issue for the contractors working on this system?
• 0:24
  All these things you need to think about as a designer when you're designing these systems We know in supermarket The supermarket industry for 20 20 years i've been in i've been applying Applying heat recovery on most of the supermarkets. So even before CO2 and now we know CO2 runs really hot discharges, which is perfect for heat recovery.
• 0:25
  This is what we're gonna be diving into and this is the things you need to know as a designer. Chris, how you doing, brother?
• 0:26
  Alright. Wow. Thanks. Having me back
• 0:27
  again. Tro. Thank you. You're the expert here. I'm just a good looking one. Well, we both are. So Chris, how long have you been employing or working with heat recovery
• 0:28
  systems?
• 0:29
  Almost my entire working life. Even though I've only been in supermarkets for the last seven or eight years. Before that, I actually was encountered these as an apprentice on dairy farms. They used to use the, use plague heat exchangers to chilled water but also another plate heat exchanger to capture the waste discharge heat.
• 0:30
  It's on R22 or 404A systems and use that to then heat hot water to then wash out the bulk melt tanks once they've been emptied to pasteurize them, to decontaminate them, or whatever the process is called. But yeah, heat recovery's been used. It's not a new technology, it's a familiar technology, it's just where can we apply it and where can we make the most of
• 0:31
  it.
• 0:32
  And that's the biggest thing, as we talked about over the last two weeks, it's understanding your customer's needs and designing around them to make sure they're getting the most effective. Piece of refrigeration equipment as possible. That's going to serve them to the best of their, uh, you know, their.
• 0:33
  Equipment can serve them, I guess. So Chris, since you start your career, you've been applying heat recovery, but it has lots of different options. It's not like you just, okay, I'm just going to take the heat and use it here. There has to be a strategy around it because. You only have so much heat in a system.
• 0:34
  And I'm, we all know different times of years, different parts of the world. You're going to have different amount of loads and that's going to really test you as a designer when you're designing with heat recovery. Would you agree with that?
• 0:35
  Yeah, certainly. So, take a standard small footprint UK supermarket, maybe 110 to 150 kilowatts of cooling load.
• 0:36
  That's sized middle of summer, when you definitely do not want space heating in that building. Dropping down part loads, you may only have 30 percent of that available in the depths of winter. Well, soon you've never not, you've not got that sufficient heat in that system to heat your entire store. You need to then think, how can we, how can we maximize this heat recovery process?
• 0:37
  Could we use a thermal store to build up heat during the warmer months and then apply it in the cooler periods? Or can we use it to supplement heat pumps or gas boilers or some other system just to top that heat process up? Or, can we look at maximising the efficiency of the building envelope and move it to an architectural design consideration?
• 0:38
  Make the size of the sales floor smaller, reduce the height of the ceiling, assuming that refrigeration duty, that low load, may be sufficient to actually heat the store. But again, it's working alongside your customer. Your design team, and making sure you come up with the best solution.
• 0:39
  And that's what we're going to talk about today, the different things about heat recovery, where we're seeing it, because I'm seeing a lot with CO2, because there's a lot of heat that you can get, and what most systems do today, we're just wasting it.
• 0:40
  Where it's going through the gas cooler, it's going through the condenser. We're just shooting it out into the air, into the atmosphere, heating up the planet a bit more. We are now, how can we be more, the most efficient and effective with a system? Because we're all about sustainability, energy efficiency, and how do we, how do we play around to make the numbers work for the customers and that design?
• 0:41
  So let's dive into it,
• 0:42
  Chris. A well designed system will lower both running costs and the overall carbon emissions of a refrigeration system. So hopefully by the end of this quick presentation tonight people should understand what we mean by heat recovery, what heat recovery is in the cooling application.
• 0:43
  understand where we can apply that heat recovery, what uses we can make for it, and then understand the factors involved in actually selecting and recovering heat on CO2 systems. Because as you touched on, CO2 is a very good working fluid, works excellently for heat recovery purposes, far better than a lot of traditional HFC, HCFC fluids were.
• 0:44
  If we look at actual heat recovery usage. Where can we use it? Number one, most supermarkets will use it for space heating. We need a lower grade heat to keep the air around people so they feel comfortable coming into those supermarkets. You can use it in domestic hot water heating. I use that term for any potable water which you can take out of the tap, out of the faucet.
• 0:45
  And then in refrigeration. More specifically, one of the main advantages we can use it for is glycol de phosphate loop heating, especially on larger scale systems, rather than having hot gas flowing through your store or electric de phosphate heaters. Use that waste heat whilst the system is running to heat up a glycol tank, a buffer vessel, or And then send that off to your display cases, to your evaporators, use that heat which you've already taken to then defrost your grills.
• 0:46
  That's a good,
• 0:47
  good point because I had Daniel Clark from Isintra on, and it's really when I first started to think about this a bit more, he's like, yeah Trevor, we don't do hot gas defrost in our systems because they do industrial. We do glycol defrost, and it made me think, wow, okay, that's very interesting.
• 0:48
  Now you're reducing maybe that thermal shock on the pipe, and I think that's one of the big keys for him, why he likes to use the glycol defrost. And anyone who wants to learn more about that, head to that podcast with Isintra on, uh, glycol defrost loop heating, because it's important, not only for a system, but But you could use it for the building.
• 0:49
  We're going to talk about using it for parking lot heat, but thanks for bringing that one up, Chris.
• 0:50
  You touched on that briefly, yeah. We don't tend to have, you know, a kingdom because our winters don't get that cold. But I imagine in Canada, and not being very far in the northern hemisphere, that'd be an excellent use for it instead of shoveling stone manually.
• 0:51
  Send a bit of that waste heat through, allow it to, allow it to melt, get your cars back in, get your trucks reversed up and all sorts. That touches on the next point. It's just effectively that heat recovery, it was almost free energy usage. Yeah. We we've already put the process in place to move that heat.
• 0:52
  Why not capture it for a useful purpose rather than sending it into the cold ambient temperatures outside? It does no one any good out there. Let's use it, capture it, put it into a buffer vessel for our space heating or our domestic hot water. We can use it to preheat incoming fresh air in an air handling unit.
• 0:53
  Send up to FANCOR units or hot water cassettes to keep a sales floor. There's so many uses for it and it's almost crazy that it's not being used up to now. Think of the millions and millions of kilowatts or BTUs that have been wasted over the past where we haven't considered this usage. And
• 0:54
  I think as we continue to evolve, we'll see more and more.
• 0:55
  I don't think I've been to a CO2 site in Canada that doesn't have heat recovery yet. And I've been to quite a few sites. So I think most of them that I've been to, it's either water reclaim, which we'll talk about, or air reclaim. Using that heat, that CO2 heat to really heat that space, like we're going to talk about in heating, uh, heating water or preheating water.
• 0:56
  And with CO2 as well, it has its own distinct advantages over previous working fluids that were in refrigerants. So just very briefly, similar typical advantages of CO2 in any situation. It's got a low viscosity, it flows around the system very well indeed. It has high thermal conductivity refrigerants.
• 0:57
  So you get that good heat transfer in smaller pipes, better efficiency in heat exchangers. Almost considered negative sometimes, high discharge temperatures. Well, when we have heat transfer for hot water or for heating, we want those high grade temperatures. That higher, that larger delta T is going to benefit us.
• 0:58
  We're going to get more heat transfer using that same fluid. And even better yet, in supercritical or transcritical mode, we have very low pinching of temperature profiles. Which is something you get in heat exchange fluids where you have a phase change, so a condenser. You can have a plate heat exchange acting as a condenser, and as that condensation process happens, we have that standard temperature.
• 0:59
  As the other fluids continue to heat up, we have a lower temperature difference as it reaches the end of that condensation process. But with CO2, well that doesn't happen, we have a constant. Decline in temperature and we just get that more efficient heat transfer It's almost it's a rouse of 10 to 15 percent over a condenser when it starts to act as a gas cooler It's it can be significant savings
• 1:00
  And that's that's interesting because this is what your customers will be looking for and this is in these calculations You really can show your customers the the the life profile like that total cost of ownership This is a big thing.
• 1:01
  We talked about it many many weeks before is Getting into that profile showing that total cost of ownership with heat recovery or without that's very
• 1:02
  important Definitely when we go into a full CO2 design core so you can actually go through the calculations using heat exchange manufacturers and a lot of them allow you to look at single phase or two phase heat transfer and you will see the actual outburn the heat recovered temperatures if you're discharging into water or die coal and you'll see the efficiency gains.
• 1:03
  It's, it's powerful stuff. So moving on, let's just summarize why Should we use heat recovery? Capture heat rather than wasting it. So number one, why waste it? Why eject it out of a building and then use heat pumps or boilers or some other fuel to then heat your building up? It makes no sense. Let's move it around and capitalise on it.
• 1:04
  Number one reason for this, it's going to reduce our electricity fuel consumption for the building. A lot of the UK supermarkets are moving away from natural gas, which is their standard fuel for heating, whether it was space heating or domestic hot water. Most of them now have some sort of heat recovery, as you've found.
• 1:05
  Even the smaller scale ones now are starting to find some payback in using it. Even with the recent addition of glass doors and glass fronted cabinets, even though our heat load is reduced, we now no longer need quite as much heat to heat the store. So it's still balancing out as we get lower down that evaporating duty that we need.
• 1:06
  And alongside that, we get improved COP of the refrigeration plant. even better yet when you look at it with, in conjunction with a heating system. So imagine you had a CO2 refrigeration system with a COP of 3 to 1, and then you'd have separate heat pumps, again with 1. When I said how in those two systems, each consuming electricity, if you combine the two, You've now got a COP of 7 to 1, because you have those three units of heat we've taken.
• 1:07
  We then use them, quickly, for the same one unit of electricity driving that compressor that's doing heating and cooling, both for useful purposes. In our building so you can get some insane efficiency gains by doing that
• 1:08
  More and more systems like that like it's you're combining the refrigeration and like a heat pump together Like it's it's really cool the dynamics of co2 and seeing this happen as it evolves Yeah.
• 1:09
  Again, even a few years ago though, I never pieced this together myself. I was actually doing some, sort of my own learning previously, and we touched on absorption chillers, and where you'd use waste heat to power a chiller. So you'd almost have it the opposite way round, so that, that heat source is now not just heating some sort of primary method, or some sort of industrial process, you're now getting cooling out of it.
• 1:10
  Or sissies. Similar principles but the opposite way around. Our primary goal is cooling, but we're getting secondary heating alongside it. It still vastly improves the efficiency of these systems. Then alongside that, increased system lifespan. If we start using it covering heat in the summer especially, we're going to see lower discharge temperatures, lower discharge pressures, and that should result in less heat.
• 1:11
  We're in tear mechanically on the equivalent but we're functioning. Now there should be less, less pressure going through our gas cooler. We may even start to drop into ordinary conditions, sub critical conditions in summer if we have a sufficient heat source to take that heat away from it before we get to the, you know, Gas unit will now
• 1:12
  condensate and that's game changing when you can design a system that can be able to do that keep that below the supercritical or Keep it at a transcritical for those hot times a year because you're using the heat That's that's a design.
• 1:13
  But once again, there's a lot of factors involved different loads that you need. Do you have that load? Or do you not have that load? And it's all going to depend on what the customer needs. And where is that? Because I really think in you said earlier, you worked in a lot of dairy. Uh dairy firms I bet in this in in the the summertime, you know, you're still going to need all that load, right?
• 1:14
  So I bet in the dairy firm and I have a good friend that pro refrigeration pro chillers. They make co2 Systems for dairy firms and I bet you The COP is amazing to be able to use that heat, and it continued the evolution of CO2 in these new
• 1:15
  designs. Definitely. I mean, even all the 404A systems in the past, we were seeing payback times on investment in under a year for the amount of hot water farmers would use, and now that is almost entirely being supplied by your refrigeration equipment.
• 1:16
  Because it's running nearly 24 hours a day to build ice, to then use to sort of quick, quickly shill, The milk coming out of the cows before it goes into a milk tank to finalise the cooling from 8C down to 10C. Two degrees cells. Yes. Instead it, that plant size is now lowered as well. 'cause we're utilizing that heat recovery into a hot water tank.
• 1:17
  It just makes everything work so much more efficiently.
• 1:18
  And they said something that the one of the farmers said in that dairy farm in the design said they're saving thousands to tens of thousands of pounds of propane. Now they don't need to use pro propane anymore. You know, they're using the system to do all the heating.
• 1:19
  So there's many advantages and it all depends on what your customer needs when you're doing this design.
• 1:20
  Let's move on. How does heat recovery actually work? So generally we're going to try and capture it, we want to put it into another fluid, so we would use a plate heat exchanger, a brazed plate heat exchanger, or some similar application.
• 1:21
  So just like the picture from Kelvin, again very well known manufacturer, at least in the United Kingdom, of heat exchangers and evaporators, condensers, gas coolers, they do a lot of refrigeration equipment. For those who haven't seen heat exchanger before, the idea is you have multiple plates, Which are butted together either held together by nuts and bolts or they can be brazed or welded sealed shut.
• 1:22
  With bolts you'll be able to take it apart, clean through the plates as they start to pile up. But there are two different methods of flowing heat, two fluids across the plate heat exchanger. So even though two fluids go through they never mix, the streams never mix. Oh, they're in contact and all the heat transfer happens through conduction through the plates themselves.
• 1:23
  So just expanding on those pictures, we have two different flow paths through. So let's take the red as our, as our refrigeration system, our hot gas from our Discharge, that's going to flow through, the other side, comes up, and then flows out the other side there. As it does that, on this, we have the inlet for, say, our, our water we want to heat up, it's going to be cold at this point, going to flow through, so the coldest part of our discharge temperature going to meet the coldest part of our water.
• 1:24
  As they flow through, the streams are in contact with each other but never mix, that cold water now exits, a lot hotter hopefully. And as we plot all the char here, We have our T1, T2, so here's our hot water coming in, or sorry, hot water. Our discharge gas flowing in into the exchanger. The heat gets taken out of that by the water.
• 1:25
  As our water flows in, flowing the opposite way, starts off nice and cold, flows in and gets warmer. And the idea of having it at both opposite ends, is that by the end of it, our water temperature can actually be higher. and the outlet temperature of our gas out of our compressor. You tend to find more simplified heat exchangers out there, which are called parallel flow, and the idea behind those is the coldest part of the fluid flows in with the hottest part of the other fluid.
• 1:26
  So, our discharge gas leaving our compressor, and then our water flowing in. But, as we'll see, the temperature, because you always need a temperature gradient of hot to cold, The temperature leaving that hot water will never reach higher than the gas itself.
• 1:27
  So one of the things that I've seen, I mean, I remember six or seven years ago when I was seeing some of these designs in CO2 systems where plate heat exchangers were starting to crack from the thermal shock.
• 1:28
  And this would be important as a designer to understand what that thermal shock or what effect it's going to have on that specific Maybe manufacturer of that heat exchanger. You want to check that design and make sure that it's those specifics because If you're running really really hot co2 and you're coming in with really cold water because that that just say it is water It may if it's coming at uh different temperatures.
• 1:29
  What what effect is it going to have on that plate heat exchanger? um Have you ever noticed that have you ever seen that before where? You There was cracked heat exchangers in a CO2 system or any system, even in general.
• 1:30
  So I've not come across one yet, generally a lot of the heat exchangers tend to be very robust working with CO2, purely I assume they're over designed because they have to deal with those high discharge pressures, 120 bar, 130 bar, let alone any bursting pressure on top of that, but I can imagine it is quite a a common occurrence.
• 1:31
  It may be different, it may be more common on different fluids rather than just water or gas. If you had other fluids which aren't meant to mix, or especially would be disastrous if they did mix, you'd obviously want to construct these heat exchangers to a much higher standard. Then again, that may be an option where you then go for your parallel flow, even though it looks less Efficient prevents that hot, well that primary fluid, the hot fluid, from reaching below a certain temperature.
• 1:32
  For example, on your, on our left side, our counter flow, if that temperature dropped below a certain level, if it was a HFC for example, you might start to condense it too early. When you might, may not want to. If you want the added efficiency anyway, you probably want to condense it early. But there's always these considerations if it's industrial processes.
• 1:33
  They may want a certain braid or certain fluid condition for other applications. I think that's beyond the scope of refrigeration we're looking at, but it's definitely a good thought experiment. I'd love to do a bit more research onto that. Yeah, and
• 1:34
  it's important to understand should you go with the counterflow or should you go with parallel flow understanding the design?
• 1:35
  What effects does it have on that specific system that you're designing and you're implementing for that customer?
• 1:36
  Definitely. So all all intents and purposes counterflow is going to be more efficient for maximizing hot water temperature If we're using a a co2 system as our hot fluid our primary fluid And water or even glycol as our low, lower secondary fluid.
• 1:37
  So for those who haven't seen the typical schematic of how a heat recovery system works, very, very basic. Just as we flow in, we have our discharge, hot gas flowing in left to right. It's going to go into a three way valve now. So in ordinary operation, if we don't want to recover that heat, it's going to pass straight through, flow through a non return valve or check valve, go into our gas cooler.
• 1:38
  Process happens as normal. If we want to start heating up some water or glycol, we can divert that valve so that all that hot gas now goes to our heat exchanger. Through our heat exchanger, our hot gas is going to flow through one side, our water or our glycol is going to flow in from the other side.
• 1:39
  It's going to warm one fluid, cool the other. Again, flows through a non return valve, out to our gas cooler. You can also get systems where it'll bypass the gas cooler entirely at this point. And it'll send that heat from the heat exchanger, straight off to our, um, high pressure valve. And into our, whatever you decide to call it.
• 1:40
  Stay, liquid receiver, flush gas vessel. All the other terms we have for them, but they could receive my terminology today.
• 1:41
  The more systems that I start to see with heat recovery, I see they start to use heat from different parts of the system as well. It's not only for heat recovery, they're taking it from the transcritical discharge side, but you're, I'm seeing more and more systems where they're taking heat from different parts of the system and utilizing in a CO2 system where I've never seen that in standard HFC systems before.
• 1:42
  For example, Heat, um, exchangers for increasing superheat. Heat exchangers for, uh, subcooling the, the drop leg as well as picking up heat for the superheat, say, on the discharge line. So you can pick up heat in different parts of the system. The most heat you're going to get out of that trans critical, uh, discharge line or the medium temp side, but you've got to look at the designer.
• 1:43
  Where can I take this other heat? Maybe it's not as hot as heat. And how do I use it effectively in a system?
• 1:44
  A tangent. I had a inquiry from a student recently about using what they termed as cold gas defrost. Like I'd never heard of this term, but the idea behind it is taking the gas cooler outlet, sending it off to your display cases and using that to defrost any ice I said, I'd never come across it.
• 1:45
  I believe it was trialled a few years back in other systems, HFC systems, and it didn't particularly work out too well. Maybe that was technology wasn't quite mature enough, may have been commissioning issues, may have been equipment selection. I said to them, if you're going to investigate this, let me know how you get on because I'd love to know a bit more about it.
• 1:46
  But it did spark my idea, but you don't necessarily just need to take it from the discharge that's the hottest part of the system. You may not want those super high grade heats. That's super high rate heat, high temperatures, where when you want a small delta T or, you know, or a saturated liquid vapor mix and send that off for me, perhaps more efficient heat transfer in that sense.
• 1:47
  There's plenty of ways and plenty of investigations that could go on on these systems. It just needs a bit more research and brave inventors out there to, uh, to come up with it. Alongside that, we talked about all the benefits of deep covering, but what about the risks of it? So, number one, most designs, as you start to add components to a system, increases the complexity.
• 1:48
  So no need to have additional parts which may fail, they may start to leak over time. You now need more controls as well, more electrical parts to go wrong. Somebody may set it up incorrectly, freeway valve might not operate, so then you're constantly supplying heat into a hot water vessel in the middle of summer when you definitely don't want it.
• 1:49
  You may have additional maintenance requirements now to clean out that heat exchanger or to clean out the body of that valve as it continues to operate. Finally, you need a skill set to understand this. You know, most of our supermarket technicians are very, very smart and they're used to controls or advanced controls.
• 1:50
  But the non supermarket, non retail, light commercial, domestic sectors, if you try to show and keep recovery in on some of that equipment, it's likely to be a bit over complicated. You may not have the expertise to work with it. So you need to then look at, is it necessarily the right application? And I've seen
• 1:51
  that over the years, Chris, over the last, say, eight or nine years, talking with people all around the world about this is like, do we have the skill set to be able to service this?
• 1:52
  Because that's what end users are worried about as well. Yes, we'll get the benefit of this heat recovery. But if I don't have anyone that can work on this system yet, that's going to cost me a lot more in the long run. So as a designer, you need to think about this, even here in North America, there's going to be different areas where you're going to be able to send a piece of equipment there.
• 1:53
  Anybody in that city is going to be able to come and work on it because they get skilled people, not anyone, but they'll have people in that town or that city to work on it. But there's other parts of North America where. You don't have that skill set, you might have to fly someone to that area or drive six, seven hours to get to that, that site.
• 1:54
  So these are things that you as a designer are going to talk about with your customer, uh, when you do add comp, uh, added complexities.
• 1:55
  Definitely. Again, I think we've already touched on this in the last few sessions, but skill set, you know, constant training is constantly evolving to encounter the new technologies and CO2 is not going away.
• 1:56
  So people are going to have to get used to working with it and it needs to become more, more commonplace. And people need to be more familiar with it, which you're only going to get by competent training and shadowing competent technicians or by following this program.
• 1:57
  Another thing that I've seen for it, you said you touched on it a little bit though, that added complexity.
• 1:58
  I was talking with a technician a few weeks ago and in their heat recovery systems, they were the ball, the three way ball valves were getting chewed out from. The high pressure. So they said they started to leak over time. And so this is another risk understanding the products you're using. Can that specific equipment that you are selecting handle that maybe that pressure or discharge pressure?
• 1:59
  Maybe you want to get heat out of it. But depending on where you, if you located the, this heat recovery system in summers where it's hot year round versus summers where it's only hot a few times a year, when you're in transcritical, and this is one thing that I learned, and I'm jumping ahead a little here, when you're doing heat recovery in the middle of winter, Versus the middle of the summer and you push it up in, and you talked about the pinch point a little bit earlier, you push it up in transcritical.
• 2:00
  That's very efficient heat you're getting from the system, um, where a lot of people think, well, you're pushing up in the transcritical, that's bad. You're using more energy. But you have a purpose for that heat into that heat recovery. So you got to think about these things and getting back that technician said they replaced multiple three way valves because of the heat recovery or the pressure behind it.
• 2:01
  So think about this as a designer.
• 2:02
  Now you go look at what components are available to you. I know that one of my other colleagues, James Bailey, has talked about when he first moved into CO2 design, they had to source components which were possibly 10 times more designed for systems, 10 times larger than what it was being applied for, purely because that's the only things out there on the market that were rated for that application.
• 2:03
  So again, as technology becomes more familiar, hopefully Designs will come out, components will be designed to match these specific situations.
• 2:04
  And I've been seeing more and more, over the last, say, 8 to 10 years, more and more, uh, industrial components coming into the commercial side. And then those industrial components getting the manufacturers making them size smaller, you know what I mean?
• 2:05
  Decreasing the size of them to, to, and then more manufacturers designing them as well. I like, we like that. We like competition. We like more manufacturers building things that makes components better, but we're seeing a lot more in the market now than we
• 2:06
  did then. Thank you, sir. It should hopefully drive the cost of the technology down, which, of course, with heat recovery, it is added components, it is going to increase capital costs of the refrigeration system, but it may have a knock on benefit that it reduces the heating costs up front.
• 2:07
  You've got fewer, well, you may have a much smaller, on your, on your heat pumps. If you're feeding building from that, or you may now no longer need a gas fired boiler, um, furnace now in the store, you know, it's got to be looked at as a holistic package. It's not just refrigeration and it's silo. It's a building service.
• 2:08
  It's the end users. Requirements which need to be taken into account as a whole. So increasing the capital cost, even though it's. You know, it's seen up front as maybe a separate budget to the lifespan, operating cost, and maintenance. It needs to be looked at as the whole package, as total life cycle cost and total life cycle emissions.
• 2:09
  So trying to sell that to the customer is very important, but likewise, we have got the scale where when it gets small enough, you add a complexity that it may double the cost of a project. If you're installing a small single back to back evaporator condensing unit split, You're not going to put a heat recovery into that because it's not going to make any, any impact on your heating requirements, whether it's a stall or whether it's a, a restaurant or any other application, like a kitchen, for example, the added complexity of that is never going to outweigh the costs or cost savings that you would have versus another heating source.
• 2:10
  And there are customers and end users out there wanting to not even have gas mains coming into the building. Anymore. I've talked to my in these conversation. How do we we don't want any natural gas or any Fossil fuels coming into our buildings. How do we do it? You know, so you're going to get into these conversations as designers And you got to think about how do you do it and you got to put your thinking caps on can we do it with this design or this design or that design because this is you're going to see more and more of this over the coming years.
• 2:11
  Definitely it's a great way to decarbonize your building especially for as an end user obviously you want to try and achieve carbon net zero, want to make our buildings as efficient as possible. This is one great way of doing it, alongside putting doors on fridges and reducing the cooling load required in the first place.
• 2:12
  Why not make use of any of that heat that you are taking out of it? It's, they're two pieces of the same puzzle really, to maximize efficiency. Those are the two main benefits we can grab very, very simply. I know there's added complexity to this, but it's, at the end of the day, it's only a handful of extra components on the system.
• 2:13
  There's nothing, you're not changing, you're not redesigning the wheel. It's just, you know, one extra valve and a heat exchanger.
• 2:14
  This is another thing too. It's going to be like a mindset shift as well, because I've had a lot of conversations with people where, you know, when you're getting heat from, say, natural gas, that's.
• 2:15
  You're getting instant heat, you know, because I'm talking with people about designing heat pumps and this like that. You're getting a different amount of heat now from like a heat pump. You're getting a different amount of heat from say a system like this versus that gas boiler. So this is where a big shift is going to happen over the years.
• 2:16
  In 20 years, 30 years time people are not going to notice this maybe, you know what I mean? But now where we're in it, like I got a natural gas furnace in my house. If I went to something like, say, this type of heat, you know, I am not getting that fire underneath, uh, underneath my, uh, into my furnace as quick, you know, so you gotta, it's going to be a shift along the way, but we're talking about how can we use it in a commercial setting, but I see it even in the residential setting happening over time, we're going to see more heat pumps, but it is going to be a different, it's not like you're going to get that 120 degree Fahrenheit heat pump, Heat right away when you're not producing that out of a heat pump.
• 2:17
  I know a little tangent there, but as a designer, you got to think about this stuff. If they're going from a boiler system to this design here, what effect is it on them there as
• 2:18
  well? I'm just as guilty as that. My house operates off of a Reverse Cycle R 410A heat pump. Actually, it's a multi split air conditioning system.
• 2:19
  But, I try and purchase electricity from a provider who uses renewable electricity. So, I'm trying to do my part for the environment there. But, on the other hand, I'm hypocrite because I have a A gas fired water boiler which does all the hot water for the house. Which, I mean, instant on demand hot water high pressure shower.
• 2:20
  It's the sort of thing you end up trading off if you're gonna go to a heat pump with a buffer vessel. You know, until I love that you're forced away from it, I might be a bit guilty in the meantime. Yeah, so as a
• 2:21
  designer, think about these different things. How is it going to affect your customer when you, when you add a design like this, so this could be one of those risks of heat recovery.
• 2:22
  Going back to what you said about customers looking to reduce or, or remove any fossil fuel supplies into their buildings, this is a great way to, Because alongside this, they're going to switch to electric heating. But that's going to involve a very large mains incoming power supply. Well, with this, we can capture some of that heat, reduce that heating loads from electric source heat pumps.
• 2:23
  It may result in a lower electrical, or smaller electrical supply to a building. Which could be potentially thousands or tens of thousands of dollars or pounds saved. Which the customer is going to thank you for. Fortunately, the main thing with heat recovery, as a critique, when it comes to it, is When do you want it?
• 2:24
  Middle of winter. When do you have the most heat available? Middle of summer. When do you have the least amount of heat available? The middle of winter. So, do we have enough heat? to supply the building. Most people have gone down the route now of even if it doesn't do the entire building by itself, it's still worth having.
• 2:25
  It outweighs the added cost of other heating sources. You already go into the effort of removing that heat or moving it from one place to another, why not take advantage of it? As we said earlier as well, the size of the system Sometimes it's a smaller scale. That's not where if you had a complexity.
• 2:26
  This is
• 2:27
  important. Cause I've been working with some, uh, some, uh, customers now where they'll do a, it's a larger, larger CO2 system, but they're using. Say hot gas defrost, but there it's a one to one system And now they're running into issues where they don't have enough heat if all the compressors satisfy They got to come up with a strategy to turn on compressors when they don't need to be on So as a designer you want to really understand that because there might be situations where heat recovery in this instance Heating for defrost prob they probably should have went with maybe electric heat heaters in that that system because now They're You have a whole big strategy for one defrost a day, because if you're not, you crash the rack.
• 2:28
  So these are important things to look at when you're designing a system. And it all comes back to the design, the numbers, looking at it. Where's your load? Moving that load. Is it the correct load to move? In the time of winter versus summer, just like you said,
• 2:29
  Chris. Especially over in the United Kingdom, we can get, well, it depends on how you look at it.
• 2:30
  What we consider to be a cold winter condition, maybe minus six Celsius outside. That's probably, I don't know how that compares to Canada. It's probably still fairly tropical. We've had experience in the past. I spent most of last January out on sites looking at the heat recovery facility of some racks, looking at why Why was the store effectively a chilled environment by that point?
• 2:31
  It was down and up, sort of, five degrees on the sales floor. Well, customers are coming in, in their coats, but the staff aren't in their coats. They're still in, Ordinary, appropriate work attire. They're going to complain. There's minimum temperature requirements in the United Kingdom. But if you don't exceed, your staff are legally obligated to go home.
• 2:32
  It is a matter of health and safety. But looking at those, it's digging into, can you verify how much of the heat we're getting out of the pack, rack? And seeing how much it's supposed to be. You know, is it doing everything it can do? It's working alongside two heat pumps. Well, should there have been three heat pumps installed?
• 2:33
  Four heat pumps installed for building? What's the original heat design calculation? If you can't find that, the pack can only do what it can do. The system is only moving the heat that it can do. There are ways around which we can mitigate or supplement that heat, we produce what we call false fluid evaporators, which are effectively large evaporator coils outside, which allows the system to act as a heat pump, but without those additions, we're going to struggle to get that heat into the building.
• 2:34
  You try and operate the pack as a, in boost mode. I think we touched on earlier where you force it into transcritical operation, take advantage of slightly higher temperature, higher temperatures on the gas. But there's only so much I can do. If you're only moving a certain amount of heat, you got to run out of steam by the end of the, uh, end of the process.
• 2:35
  Yeah.
• 2:36
  And it's all about design. Goes back to design and the numbers.
• 2:37
  Exactly. You need to run your design and determine, is it worth it? Fingers crossed the most retail applications. It probably is. So, we haven't got enough time today to touch on it, but there's so much we can cover on heat recovery, especially when we're looking at designing a supermarket.
• 2:38
  Almost want to spend as much time on a good heating design as you would on your cooling design, but that's a completely different specialization. As long as we can understand or appreciate it, we can do our part to play, play our role in that process. So, again, looking at actual design and selecting Bravesplate heat exchangers, science in itself.
• 2:39
  You have different calculations, log mean temperature difference, and all these, uh, fancy equations. False load evaporator coil sizing. So you'd look at what heat do we have at lowest condition in our supermarket? What's our heat load? Well, can we supplement that heat with false load evaporator coils? May have one, two, three, just act as a heat pump.
• 2:40
  They're still using that one system to move that heat and put it into where, where we want it, where we desire. Look at control systems, control logic, how do we know how to operate this? Do we want all the heat to flow through this buffer vessel? Well, that may be too much. We've worked on the assumption through this presentation that we want to capture all the heat if it's available all the time, but we mainly have a very small heating requirement and a very large cooling process going on.
• 2:41
  Are we to be able to open a valve to divert just enough hot gas to heat that fluid, whether it's glucol or water? Whilst the rest of it will flow through to our gas cooler. So it's looking at different control strategies, how we can use it alongside other heating sources. Do we want our CO2 system to operate as a baseload of heat?
• 2:42
  And then supplement it as we step up with heat pumps, boilers, etc. Or 1, 2, 3 heat pumps, stage them. We can look at all that. And then more importantly, probably for our customers. If you look at the life cycle costs and total life cycle emissions, what impact are these heating systems or this heat recovery going to have on the building?
• 2:43
  Is the extra 10, 000 upfront going to potentially offset 100, 000 in energy usage? Well, if they're the owner of the building and operating it. Yeah, great. But if they're, uh, a landlord looking to just pay the lowest cost up front, I mean, not, not concerned with the tenant's operating costs, it may not be, uh, on the top of their list.
• 2:44
  That one there's key is understanding your customer and that relationship that you have. With them because that's a good point that I was uh did a podcast last week And that's what they talked about like a customer has now Uh building lease for 15 years. That's a big difference than if you only get a one year building lease What are you going to do?
• 2:45
  Do you want to be more sustainable over 15 years because you know, you're in a lease now for that long or like you said Is it just okay next year i'm going to go find another place. So these are things that you want to Build a relationship. This is a little more than just the design world, but build that relationship.
• 2:46
  So you understand where your customer's coming from.
• 2:47
  And they may be the same customer, but different departments and therefore different budgets. Their installation budget may be completely at odds with their maintenance budget, but you need to make sure it works best and try and guide your customer towards the best engineer solution.
• 2:48
  Looking at that total life cycle cost and total life cycle emissions, because at the end of the day that's, that's where you demonstrate your good engineering competence. Looking at compressor selections, how we maximize that heat recovery performance. Obviously there's different compressor types out there, they're going to produce different discharge temperatures as well.
• 2:49
  Looking at how, just how efficient they are in these applications, you may select a different compressor just to get the added heat out of it, then you would another compressor which runs at a lower discharge temperature. Even though one might live better in the middle of summer, how many months of the year do you have this requirement for heat recovery?
• 2:50
  Well, over in the United Kingdom, we probably need heat recovery for 8 months, if not 9 months of the year sometimes, where our high peak temperatures in summer, we may only peak for 2 months. So, it's again, it's weighing up, it's looking at the current application. If you're in, take North Africa for example, or um, Middle East, so really hot, dry environments, eRecovery may be great for hot water cleaning applications, maybe in industrial processes, but you're not going to need space heating unless it's the middle of the night, which, how often are your customers going to be back?
• 2:51
  And you have to weigh it up. That's how it all comes down to calculating that part load heat available. Conditions are going to be worst case. We design our cooling systems to worst case. Highest temperatures, highest cooling duties. Similar to this. We can have a balance there. What's the lowest ambient temperatures or highest temperatures we need in our store?
• 2:52
  How can we balance it out? And it's all stuff which is so much information you could cover on heat recovery. It's a separate, not an industry in itself, but it's a very complicated topic and you could easily spend years researching and investigating this and still not become. Yeah, you know, a hundred percent knowledge over it, or, I mean, I don't think we can on any, any topic ever, you know, there's always something to learn isn't there, but this is, this is a really exciting topic in evolution for the industry.
• 2:53
  Maybe start realizing that QD engineers and refrigeration engineers are just as much experts on heating as heating engineers are, you know, we're, we're the experts in moving. Energy, which is a basis of all heating. But instead of just lighting a fire, we have to have a four part minimum mechanical cycle going on.
• 2:54
  So he was a real expert. So, yeah.
• 2:55
  Yeah, that's exactly what I was going to say. So he took the words out of my mouth and this is all the things that are going to be in this advanced CO2 design course. As an engineer, you got to understand all these, this is how you bring the most value to your customer. So if you're interested in this.
• 2:56
  Email me and we'll let you know about this program because it's going to be a game changer, especially we're going to see co2 continue to grow, especially here in North America and globally. You want to be the best prepared for when your customer starts coming to ask you and in some areas right now, it's.
• 2:57
  That's what is going it's going co2 because the legislation and the regulations you want to be the best prepared designer out there Reach out to me and I will definitely talk to you and show you a little bit more what is involved in this advanced course It's definitely not for beginners. Just letting you know.
• 2:58
  This isn't an advanced course So you gotta be doing it for a few years design already. So i'm excited chris. I'm excited
• 2:59
  When do you actually start having those high level conversations and getting into the nitty gritty of system design and peculiarities and non idealities and seeing that's great in theory, but actually my site has this or I don't have this.
• 3:00
  12 foot, well, you know, 120 foot K 144. How's that going to impact on this system, especially if you are when adding to an existing system? How's that gonna impact everything from down the line? And you can get into a real detailed conversations and find out that extra knowledge and just make everyone a better designer or better engineer at the end of the day.
• 3:01
  And it's putting
• 3:02
  the work in, you put the work in now and it's gonna pay off later. When you're either looking to help your customers, looking for a new role at another engineering organization or design firm, because building your knowledge is going to build your career. For sure. Chris, love it. How can people find out more about you, Omega Solutions, as well as this program?
• 3:03
  This is where it'd be really great if I had a slide on this presentation, which had all my contact details, but unfortunately I don't, um, you can find us on LinkedIn. I know it's just Amiga solutions now, actually. We changed the name recently because it was originally Amiga solutions brackets cross hills, which is where our office is located, but we're now the largest Amiga solutions on LinkedIn.
• 3:04
  So we've scrapped the last bit. We are just Amiga solutions. Find us on LinkedIn there. You can find me on LinkedIn, Chris Griffiths. You can find the rest of us on there. If you click on through website, or you can contact me by email Chris at Amiga hyphen solutions. Dot co dot uk mother
• 3:05
  chris. Thank you so much brother next week We're going to be diving in how to size the refrigeration Pipe work.
• 3:06
  This is going to be key as a designer because this is where i've even seen it now Where sometimes the design can get in a lot of trouble if you don't design the pipe or pressure drops Risers, do you take the pipe off the side or the bottom? Lots of different things about co2 these little tips and tricks for the mass flow now We're running Pressure's way higher, different velocities, and this is going to be a key, so next week, get here.
• 3:07
  Tell your friends about it because those designers are going to want to learn about this pipe work design. So, Chris, thank you so much. Thanks everyone for joining.
• 3:08
  I
• 3:09
  want
• 3:10
  to thank you so much for hanging out with me and the Refrigeration Mentor podcast. If you enjoyed this episode, please leave a comment.
• 3:11
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• 3:12
  If you have not been to the refrigeration mentor website at refrigeration, mentor. com, go check it out. There's a ton more guest podcasts I've been on as well as the event page. Check out the events page because there's a lot more free trainings as well as
• 3:13
  paid training to really help you grow your
• 3:14
  knowledge base.
• 3:15
  Super excited. Can't wait to see at the next refrigeration mentor podcast. Let's get a conversation going.