How Cooling Towers Work

Hi there Paul here from TheEngineeringMindset.com. In this video we're gonna look at the operation of a cooling tower. So just as a quick overview of what to expect from this video we're gonna look at the operation of this cooling tower here. And we're gonna look at how the warm water, which is being sent from the chiller and contains the heat from the building, which needs to be rejected. That's going to enter this header, pass through this spray nozzle and be distributed over this packaging. That warm water will then loose some of it's heat as it makes it's way to the bottom here. It will drip down and then collect into this basin. And the cooler condenser water is then collected from the basin, sent back down to the chiller where it will pick up that heat again and be sent up in a continuous loop there. Meanwhile cooler air / ambient air is being sucked in to this cooling tower. That passes in the opposite direction of the condenser water and that picks up the heat from the water. But as it does that it'll also pick up some of the water making this very humid and very moist. So we've got this drift eliminator at the top here and that will condense some of that water so we can reclaim it and keep our operating cost down. And that humid air, you know it's lost some humidity here; that is then rejected by this fan and pushed out into the atmosphere. We're gonna look at each part of this in much more detail, so you can skip through the video if you need to just see a certain part, but let's crack on. Cooler towers are, I've said on the previous video, but these are really used on every single building, large building. Just the type of cooling tower will change. Some will be kind of open wet cooling towers and some won't. It all depends on the design criteria. So as you can see on the screen we've got a little model of a cooling tower which I've made here. In a real world example of one of these types of cooling towers will look something like this. This is Belty Aircoil Company cooling tower. We're gonna run through how one of these works and what it is used for. So in building services these are used on almost every single office building around the world depending on it's size. They're very effective at rejecting heat. So what happens is; you use these to reject the heat from the building. So all the heat gets picked up from people, computers, machines, lighting, all the solar gain, all of that heat needs to be removed from the building to keep it cool. So that's picked up by a chiller and it is sent from the condenser up into ones of these, which is a cooling tower. And the purpose of this plant item here is to take water in at a certain temperature and put it back into the building at a much lower temperature so that it can pick up more heat again and send it back to be chucked out of the unit. So let's have look at some of the components in there. You'll see on the top we've got a fan. So this fan obviously spins and as it does so it pulls air out of the unit. Air flows in, fresh air, ambient air, air around you flows in from these panels here, which it just filters. They've got an inlet shield just to stop sunlight and dust and bugs, maybe animals, even children getting in there. (laughing) So the air comes into this point here and then makes it's way up and gets pulled out of the cooling tower at the top here. And on the outside we've got a motor here. And on this example I've just made a simple belt drive system which pulls that fan. But the motor could be mounted inside or it could be a gear ratio or something like this. But we're just keeping it very simple on this one, so I've put a belt system on there. And actually let's have a look inside the unit here. So, this is a peek inside the unit. And as you can see we've got some pipes here with some funny looking plastic parts here and here. And a few other little pipes. And let's just change view there. So, the condenser water which is the warm water that's being collected from the building and being sent up by the chiller, that enters through this pipe here and it enters into this header and that warm water is then sprayed out of these spray nozzles. In the real world the spray nozzles coming down onto the packaging will look a bit like this. So these nozzles here kind of this and they're just spraying down across this fill packaging. On to this which is known as the packaging or the fill. In the real world the packaging will look something like this. And the purpose of this fill is that the water, the condenser water will run as it sprays in really fine particles and it collects and runs down the sides of this in a thin film. Now the air which is rushing past the other way picks up heat from this because if you let it just kind of run out then it's got a small surface area, but if you spread it out and put across the really thin film, across all these packaging sheets, which is made of a type of plastic then that increases the surface area. And so you're maximizing the area that the air can reach or can touch. And so once it does that it pulls the heat out of that water. The water, the condenser water will then roll down the side here and drip down and collect down here in the basin. And that warm air will enter through these sides or these panels here, make it's way up through these grills or the fill packaging, past this pipe work, up out through the drift eliminators, and then out through the top. As that water pours out of this pipe work here and it sprays and becomes a thin film along this fill packaging here what we're gonna find is that some of the water will evaporate, which takes some of the heat away. But we're gonna lose moisture to that as well. So the purpose of this which is called the fill packaging. No it's not sorry it's called the drift eliminator. What happens is the air enters into here, it's being pulled by this fan at the top here and the air is coming in at a high velocity and it's impacting, it's hitting against the surfaces. It's gonna make these really sharp turns to get out of the system and get to where the fan is trying to pull it out through. So as it does this and it's colliding with the sides and that's giving the moisture in the air a chance to condense on the sides and then run down. So the more impact it makes the more it's condensing that vapor in the air and allowing it to condense and pour away. So we'll reclaim some of that water, which would otherwise have lost and be sent out to the atmosphere. Down in the basin here we have got a number of pipes. We'll see the biggest pipe here. It's about a six inch pipe and that is the outlet. So this is the condenser water return, which is gonna go back down into the building and down to the condenser of the chiller. Over here we've got the water inlet and that is connected to a ball valve. So as the water level gets too low this will allow more water to enter the tower. And keep this filled to a certain level. Over here we've got the over flow. So say this was to have got stuck, something like this water would pour in here to fill it up, but there's no where for that to go and you don't want it to fill up and start going through the tower out the sides here. So we've got an overflow here. Just to take some of that flow away. And then the last part here we've got is the drain. So the drain is quite important because in the water that's entering this tower here, the water contains salts and bacteria and stuff like that and as this water evaporates it's gonna leave behind that salt and the gunk and muck that's contained within the water. And that salt won't evaporate. That will start to collect up here in the basin or up on the fill packaging etc. And so once it reaches a certain level this will need to drain, so the cooling tower will be told to dump a lot of the water that's in this tower down to drain while they add fresh water. Not through that one, sorry through this one. They add fresh water to this system in through here or through the condenser water inlet there. And once that has reached a certain amount of parts per million the minimum threshold, that drain will close and it will continue in it's cycle of operation. And that's really it for a cooling tower. Well for this type of induced draft open cooling tower. There's lots of other types of cooing tower and we'll run through some of those in our other videos. Thanks for watching.

Channel: The Engineering Mindset

Views: 383,670

Keywords: nuclear, nuclear power, Nuclear Power (Industry), cooling towers, Cooling Tower, Atmospheric, Mechanical, Natural Draft, Forced Draft, Induced Draft, Hyperbolic, Fans, Basin, Heat Exchanger, Cooling, Towers, Chillers, Chiller, training, classes, HVAC, Basics, Fundamentals, AC, Air conditioning, Cooling Tower (Building Function), condenser, evaporator, building services, engineer, engineering, theengineeringmindset, learn, free, central plant, plant, thermodynamics, tehcnician, 3d

Id: UzHJWNL2OtM

Length: 13min 0sec (780 seconds)

Published: Sat Feb 27 2016