Questions tagged [refrigeration]

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What's the lowest ambient temperature a refrigerator will work in?

Assuming a standard domestic refrigerator that uses R134a, I can see only two reasons a vapor-compression cycle wouldn't work. Either the ambient temperature is so low that the R134a freezes in the ...
Björn Morén's user avatar
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Explanation of phases of fridge cycle from power draw (power factor, reactive and active power)

I've got this power draw graph of my fridge during a couple of cycles. The power factor axis is on the left, active and reactive power axis in watts/VAr on the right. I'd like to understand the phases ...
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Refrigerant flow

I am an HVAC engineer. I know that in the refrigeration cycle the expansion valve controls the refrigerant flow rate but if flow through a positive displacement compressor is fixed, how does it do ...
Moein Seyedjafary's user avatar
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Suggestions for estimating Heat Load (watts) in an evaporator (antifreeze - hot fluid, R744 - cold fluid)

I am working on simulating an evaporator for an R744 refrigeration cycle. Here, I have inlet conditions of R744 with low pressure (around 30 bar) and low temperature(-8°C) and that of antifreeze (35% ...
ascruine's user avatar
1 vote
2 answers
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How does an expansion valve cool fluid?

How does fluid loose temperature after leaving an expansion valve in a refrigeration cycle? Where does this heat go?
leoJ's user avatar
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Home freeze drying

I want to make a freeze dryer to preserve fruits/foods. I can get a vacuum chamber here: https://www.aliexpress.com/item/1005002865276963.html and i can put that into a chest freezer. I had a look at ...
pgee70's user avatar
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2 answers
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Methods for precission control of a freezer cooling output

I am doing some experiments in fractional freezing with a modified residential deep freezer. I have programmed my own PID controller on an Arduino setup such that it will not cycle the refrigeration ...
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what is effect of temperature on dew point?

I read that relative humidity changes with change in temperature though there can be constant humidity. So, if RH is changing then dew point should get increase with increase in temperature? https://...
Rohit's user avatar
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Use of nozzle as a refrigeration device

When compressed air passes through a nozzle, its velocity increases while its temperature decreases due to the pressure drop. Why is this process not utilized as a refrigeration system similar to air ...
Max's user avatar
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1 answer
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What is the behaviour of water at a pressure reducing valve (PRV)?

Suppose I pass water through a pressure reducing valve, which can lower the pressure enough for the water to boil, will the water fully boil? If so, what would happen if that vapour passed to a tube, ...
Belal Bahaa's user avatar
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1 answer
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Why should a refrigerant have low melting point?

I have been reading about refrigerants lately. I understand that a refrigerant should have a low boiling point; however, I don't understand why it should have a low melting point. My instinct was ...
Belal Bahaa's user avatar
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Working principle of Ranque–Hilsch Vortex Tube

I am not able to understand the reason for temperature separation and flow reversal in a counter-flow vortex tube refrigeration system. As per some sources, "Compressed air is passed through the ...
MechaTrex's user avatar
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2 answers
412 views

Why do we need a compressor to heat vapor in vapor-compression refrigeration?

I'm reading the Wikipedia article on vapor-compression refrigeration. In the cycle, first the refrigerant absorbs heat from the source to be cooled, which causes it to be vaporized. Then this vapor ...
S. Rotos's user avatar
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Why air cannot be used as a cooling medium in CO2 refrigeration system?

Can anyone please explain the reason for above question?
Chandan Gupta's user avatar
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1 answer
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Why regulations on refrigerant and not on efforts in preparing standard for leak proof refrigeration system?

Refrigerants from CFC series are banned due to environmental concerns,but why not focus on preparing a standard for registration system which minimize or eliminate leakage? It must be difficult to ...
Crazy_Court651's user avatar
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Does pressure/temperature drop in a funnel or nozzle with a gas being pumped through it by a fan

So, I was thinking about trying to build some kind of body cooling suit and started looking into the wonderful world of refrigeration systems. I've managed to get myself side-tracked pretty badly ...
David Nolan's user avatar
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How does compressor ensure that rfgnt exiting the compressor exits at sufficient pressure such as its condensation tmp is always > otsd air temp?

I have very basic knowledge of the refrigerant cycle. I am talking about a Split system Home AC with an air cooled condenser. Assume a basic AC reciprocating or scroll compressor (i.e NOT a variable ...
Sanjay Biswas's user avatar
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2 answers
2k views

At what refrigerant pressure does an air conditioner blow coldest?

R-134a refrigerant has recommended pressure levels to keep a system properly charged: My question is if you're trying to make an ac system as cold as possible, and you're willing to ignore potential ...
YAHsaves's user avatar
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4 votes
2 answers
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Cooling system to maintain 0.5 °C at 95% humidity

I am looking for some guidance on a redneck cooling system. I need to store seeding trees at a temperature just above freezing, and at a humidity of close to saturation. I only need the system for ...
Sherwood Botsford's user avatar
-1 votes
1 answer
71 views

Identify this textbook

I would really like to buy this textbook, but only see a scan of one chapter online. Could anybody help me identify the book? Thanks!
Rav4's user avatar
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1 answer
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Dehumidification calculations

I'm looking at options for DIY dehumidification and am hoping to get a sanity check on some calculations, and verification that I'm using the right factors in the right way. As a reference point, I ...
fixer1234's user avatar
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Why are there no propane refrigerator air-conditioning units that run on solar heat?

I was thinking about how hot it was outside, when a thought came to me. There are propane refrigerators, so why not replace the propane as the heat source with solar heat and then change it from a ...
Adrian's user avatar
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2 answers
154 views

Copper pipe for brine water block ice system

I am looking to replace copper pipes from a brine water block ice system . The pipes needed are 5/8 but wonder what wall thickness it should be. They should be thick enought to withstand 60 psi ...
user2019838's user avatar
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2 answers
794 views

Can Peltier Modules be used as an Air Conditioner? [duplicate]

Air Conditioners are very expensive so I'm planning to build a split type air conditioner using Peltier modules for my sealed room that is 6.5 length, 7 feet height, and 5.6 wide. I plan to use nine ...
Zaxs Argam Lagard's user avatar
5 votes
0 answers
111 views

Why is there limited use of Y (Wye) fittings in a refrigeration system?

I'm a Mechanical Engineering intern currently working in HVAC and Refrigeration for grocery stores. I'm looking into ways, with lower energy losses, to encourage equal flow distribution at liquid pipe ...
Lamijops's user avatar
2 votes
2 answers
430 views

How to increase temperature of the condenser part in a refrigeration cycle?

I have made a refrigeration system at my home. I am using r134a as the refrigerant. I want to achieve a temperature of about 70-degree Celcius in the condenser part and 0-degree Celcius in the ...
Tank's user avatar
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What if ammonia is used as a refrigerant for a refrigerator?

I have a refrigerator whose compressor configuration is: power- 10hp compression ratio- 10:1 I do not have expertise in this field, but I am curious if I use ammonia as a refrigerant instead of HFC-...
Tank's user avatar
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1 answer
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How is heat transfer calculated for an aqueous salt solution?

I am familiar with using $\dot{Q}=c_p\cdot\dot{m}\cdot\Delta T$ to calculate the heat transfer rate of a fluid given a singular value for specific heat capacity (such as with water), but how do I go ...
Jason Ogden's user avatar
6 votes
2 answers
157 views

Why aircraft refrigeration uses a centrifugal compressor in place of reciprocating compressor?

Why aircraft refrigeration uses a centrifugal compressor in place of reciprocating compressor and a gas turbine in place of reciprocating expander?
Millie's user avatar
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2 votes
2 answers
150 views

RV HVAC and Fridge Freezer on the same coolant loop?

Given the space, weight, and power constraints of an RV it is useful to make as much use as possible out of every component. Is there an engineering reason why a refrigerator / freezer and an air ...
John F. Miller's user avatar
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1 answer
31 views

Has anyone built a heat powered vapor compression cooler?

I've had this idea in my head for a refrigeration cycle which is powered by heat, uses only one fluid, and whose only moving part is the fluid. I would like to know if my idea is new, or if it's ...
BenGoldberg's user avatar
4 votes
2 answers
16k views

Can Peltier Modules be practically used to cool a room?

I am thinking of building a indirect Peltier AC to cool a room of approx size 30m3. Single/multiple Peltier modules will be used to cool a insulated box with water inside. The box will be kept outside ...
Aman Agarwal's user avatar
1 vote
0 answers
63 views

Can any Air rotameter be used for refrigerant gas by using equation conversion?

Currently, I am trying to find rotameter calibrated for R134A gas flow. However, most companies only sell rotameter or variable area flowmeter for water/Air/Nitrogen flow. Is it possible to use any ...
HENG KIM RUI's user avatar
4 votes
3 answers
1k views

Can a Peltier's device (i.e.Thermoelectric cooler) achieve cryogenic temperature efficiently?

Does the stacking of peltiers device shows promising results in achieving the cryogenic temperature? I have tried doing the experiment, the overall temperature of the system increased around 80ºC and ...
Adarsh Shubhananda's user avatar
2 votes
1 answer
727 views

Modelling a refrigeration cycle in Excel

Is it possible to model a heat pump cycle without using tools like EES, but using Excel? I am considering to use Refprop application as an add-in in Excel, and model a heat pump cycle. Another ...
 xavc's user avatar
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1 vote
0 answers
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DC Inverter motor AC utilization category

I am looking at specs of an air conditioner unit. It uses DC inverter technology and maximum current listed as 21.5A So are DC inverter motors considered resistive or inductive? What utilization ...
yurtesen's user avatar
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2 answers
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What is the idea behind an expansion valve?

I am watching this video(https://www.youtube.com/watch?v=gVLhrLTF878) and beginning at around the 2:20 mark, it explains the significance of an expansion valve with the following ideas: Restricts ...
TheLast Cipher's user avatar
2 votes
3 answers
614 views

1 Ton of Refrigeration

"1 TR is equivalent to the rate of heat transfer needed to produce 1 U.S. ton (2000 lbs) of ice at 32F from water at 32F in one day, i.e., 24 hours." While defining 1 Ton of Refrigeration (TR), why ...
hkishnani3's user avatar
1 vote
3 answers
993 views

Relative inefficiency of doorless fridges at supermarkets

It appears to be a waste of electricity to keep a bank of refrigerators wide open with no doors or covers whatsoever on them. They seem to be just blowing cold air out into the supermarket. They ...
NoName's user avatar
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0 answers
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Dimension of an evaporator coil

I need to cool 3 galons of water from 77 to 32°F to form an ice bank that I will use to cool beer (it is a noble effort, you see). I figured I need to install a cooling capacity of 0.34 kw to lower ...
sergio lopez's user avatar
0 votes
2 answers
198 views

Save money with using a refrigerator correctly - blowing cold air to the back of it?

We are heating up our houses in winter to ex.: 21C to then have an insulated box inside the house, which we cold down to 5 and -15C, and we call it a refrigerator.. :) The situation: we would buy a ...
hans4432's user avatar
0 votes
1 answer
57 views

Is there any practical way to partially absorb the heat from a refrigeration condenser

I have currently been experimenting with a phase change material to absorb the heat given off by the condenser in a small refrigeration system (about 1/5 hp compressor) and while it does absorb a ...
Hishalv's user avatar
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1 vote
2 answers
226 views

Why is the saturation pressure of the refrigerant desired to be slightly greater than atmospheric pressure in an evaporator?

I read that it "is a positive pressure against the environment". But I am not too sure what that means.
Shah M Hasan's user avatar
12 votes
5 answers
42k views

Should we protect our AC's outdoor unit from sunlight?Does it increases the durability of an AC and its refrigerant if it is well shaded?

My AC outdoor unit gets direct sunlight (no shading whatsoever) from morning to noon. Temperature normally soars up to 40 degree Celsius (I am from India). I have two questions: Is this bad for the ...
Paran's user avatar
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3 votes
1 answer
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Store seeds at 1°C

I have prunus pits that I stratify in a refrigerator during winter. Normally, the seeds germinate in springtime, which is ideal. However, often some of the seeds germinate prematurely. When this ...
User1974's user avatar
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2 answers
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How to prevent ice build up in a refrigerator?

There is ice build in my Samsung RF266 refrigerator. I have posted the following questions in Home Improvement Stack Exchange hoping to find a solution. The questions are as follows: Samsung RF266 ...
DiaperHands's user avatar
1 vote
1 answer
61 views

What will remain constant during the circulation of working substance in a refrigerating machine? [closed]

For Example, the pressure of evaporator can be changed, also the pressure of condenser and many more parameters. What is that parameter which remain constant while others keep changing ?
Zaid AAmir's user avatar
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1 answer
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How to compute the performance of a refrigerant?

As I understand it, there are 5 key factors that determine the performance potential of a refrigerant gas: Vapor density Enthalpy of vaporization Thermal Conductivity Critical temperature Specific ...
Wallace Park's user avatar
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21 votes
6 answers
231k views

What's wrong with transporting a refrigerator on its side?

I tried to deliver a refrigerator and the customer saw that the refrigerator was lying down in the truck instead of standing up. He refused to accept it, claiming that the compressor would be damaged ...
0tyranny0poverty's user avatar
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1 answer
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How does Work behave in two different refrigeration setup?

Does work behave the same way for all temperature range while in a refrigeration setup. When quality of heat changes with the temperature, Does it apply to work also. IF we consider refrigerator ...
aakash dv's user avatar