00:00:04.250 [Music] 00:00:06.50900:00:06.519 in the last video we talked about the 00:00:10.57000:00:10.580 expansion device here now this one's 00:00:13.20900:00:13.219 about the evaporator that's this part 00:00:15.97000:00:15.980 right here be some sort of coil the 00:00:19.68900:00:19.699 transfers heat this is a compressor 00:00:22.48000:00:22.490 that's the suction side of the 00:00:24.07000:00:24.080 compressor that's a suck side once the 00:00:26.95000:00:26.960 refrigerant passes through the expansion 00:00:30.22000:00:30.230 device which is a restriction it's 00:00:33.04000:00:33.050 temperature and pressure are both lured 00:00:36.10000:00:36.110 the pressure is lowered because of the 00:00:38.95000:00:38.960 restriction of the expansion device once 00:00:43.72000:00:43.730 that pressure is lowered the refrigerant 00:00:46.63000:00:46.640 inside here will boil at a lower 00:00:50.53000:00:50.540 temperature than the surrounding air of 00:00:54.97000:00:54.980 the evaporator know we're using an air 00:00:57.52000:00:57.530 evaporator we could use water or brine 00:01:00.49000:01:00.500 and all sorts of things but generally 00:01:02.89000:01:02.900 it's going to be an evaporator that's 00:01:05.43900:01:05.449 exposed to air the effect of the 00:01:08.31900:01:08.329 evaporator is the reason we do 00:01:11.23000:01:11.240 refrigeration at all just to get stuff 00:01:13.41900:01:13.429 cold so this is boiling at a temperature 00:01:17.95000:01:17.960 below the air passing across the coil so 00:01:21.96900:01:21.979 it's going to boil and as it comes out 00:01:24.37000:01:24.380 of this expansion device that's a warm 00:01:28.33000:01:28.340 high pressure liquid as it comes through 00:01:31.64900:01:31.659 it immediately has to reduce the 00:01:35.21900:01:35.229 temperature of the liquid to whatever 00:01:39.42900:01:39.439 temperature it's boiling at part of the 00:01:42.48000:01:42.490 evaporation takes place just to reduce 00:01:45.16000:01:45.170 the temperature of that liquid as it 00:01:48.06900:01:48.079 comes soon let's say the liquid comes 00:01:49.62900:01:49.639 through at 100 degrees and I'm boiling 00:01:54.03900:01:54.049 at 40 here in the back well it's that 00:01:58.56900:01:58.579 sensible he has to be taken off of that 00:02:01.09000:02:01.100 liquid refrigerant and so that's the 00:02:03.16000:02:03.170 first short section here it reduces that 00:02:07.59900:02:07.609 sensible heat off the liquid and gets it 00:02:12.58000:02:12.590 down to 00:02:13.69900:02:13.709 the boiling point actually that can be 00:02:15.97900:02:15.989 up to 25% of the load is just removing 00:02:20.63000:02:20.640 that sensible heat so that's the first 00:02:24.97900:02:24.989 thing it does as it starts boiling then 00:02:29.56900:02:29.579 it starts taking heat out of the air 00:02:32.50900:02:32.519 passing across the quarter now 00:02:36.28900:02:36.299 throughout this whole thing this is just 00:02:38.66000:02:38.670 a bubbling mess there's no bubbles 00:02:40.81900:02:40.829 coming up there it's all it'll sit there 00:02:42.94900:02:42.959 absorbing heat now here's where the 00:02:45.97000:02:45.980 expansion device has so much affect on 00:02:48.71000:02:48.720 this thing we do not want this entire 00:02:52.06900:02:52.079 coil filled with boiling liquid 00:02:55.97000:02:55.980 refrigerant the reason being we don't 00:02:59.30000:02:59.310 want to dump the liquid into this 00:03:02.05900:03:02.069 compressive compressors our gas pumps 00:03:05.17000:03:05.180 they will pump gases they don't do so 00:03:09.83000:03:09.840 good pumping liquid there can be lots of 00:03:12.58900:03:12.599 damage and so on like that 00:03:14.50900:03:14.519 so we want all of this refrigerant to 00:03:18.74000:03:18.750 boil off before it gets to that 00:03:21.68000:03:21.690 compressor if the expansion device is 00:03:24.40900:03:24.419 doing its job then by the time we get 00:03:27.77000:03:27.780 somewhere around in here we're gonna run 00:03:32.24000:03:32.250 out of liquid it's going to be 00:03:35.50900:03:35.519 completely boiled off if it is 00:03:39.11000:03:39.120 completely boiled off at this point then 00:03:41.36000:03:41.370 just a pure gas comes back to the 00:03:45.02000:03:45.030 compressor that is normal operation for 00:03:47.65900:03:47.669 these things you can have all sorts of 00:03:49.67000:03:49.680 things happen work that doesn't work out 00:03:52.69900:03:52.709 and there's liquid coming back you know 00:03:56.36000:03:56.370 when you block the evaporator coil with 00:03:58.78900:03:58.799 a plug filter or something like that 00:04:00.02000:04:00.030 that can change it refrigerant charge if 00:04:04.39900:04:04.409 the charge is too low then instead of 00:04:06.89000:04:06.900 boiling off here it boils off 00:04:08.71000:04:08.720 down here someplace and you don't get 00:04:12.42000:04:12.430 very much effective cooling so this 00:04:16.15000:04:16.160 thing working properly could feed the 00:04:18.59900:04:18.609 proper amount of refrigerant into this 00:04:21.16000:04:21.170 coil so that we run out of a liquid 00:04:25.57000:04:25.580 about this point and the gas does what's 00:04:29.17000:04:29.180 called superheat that means it warms up 00:04:33.37000:04:33.380 from the tower the saturated temperature 00:04:37.27000:04:37.280 pressure that was happening here in the 00:04:39.97000:04:39.980 middle of the coil and then it runs back 00:04:42.73000:04:42.740 to the compressor and cycles around 00:04:44.38000:04:44.390 again fairly simple you can see and 00:04:48.91000:04:48.920 we'll talk more about these later all 00:04:51.10000:04:51.110 the things that could affect this you 00:04:54.46000:04:54.470 know refrigerant charge could affect how 00:04:58.00000:04:58.010 much refrigerant gets in here head 00:05:01.30000:05:01.310 pressure could affect it blocking 00:05:03.57000:05:03.580 blockage of filters coils being plugged 00:05:07.30000:05:07.310 not enough airflow all those things can 00:05:09.55000:05:09.560 affect the way this floor okay the next 00:05:11.44000:05:11.450 thing we're going to go into is a 00:05:12.76000:05:12.770 compressor now the compressor is gonna 00:05:14.71000:05:14.720 be one of the most complicated parts of 00:05:18.79000:05:18.800 this refrigeration system it's also the 00:05:21.28000:05:21.290 most expensive light rail so we will 00:05:25.36000:05:25.370 continue on with the compressive not 00:05:28.45000:05:28.460 saying I'm not going to have more on 00:05:29.95000:05:29.960 about there got plenty more on that 00:05:31.86000:05:31.870 that's it for this one
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