# What is Cooling: Definition and 639 Discussions

Cooling is removal of heat, usually resulting in a lower temperature and/or phase change. Temperature lowering achieved by any other means may also be called cooling.
The transfer of thermal energy may occur via thermal radiation, heat conduction or convection. Examples include:

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1. ### A discontinuous refrigerant cycle

Hi there, I went to a learning visit to a small plant where it was intended to use a refrigerant cycle to cool down water used in a heat exchanger; from what I've gathered they had to stop using the refrigerant unit altogether as they're doing little batch productions per day, resulting in...
2. ### Rated Current and Current in mini split Air Conditioner

Hello, I am seeing two mini split ACs with the same cooling capacity in two different companies. Both 24000 BTU and Inverter. The first one said Rated Current is 9.56 A and didn't write Max current or current. The second one said the Current is 9.9 A and the Rated Current is 16 A. Does...

Thanks!
4. ### Second order differential - Tanks in series cooling coil

I'm stuck on a problem: T1 = dT2/dt + xT2 - y T2 = (Ae^(-4.26t))+(Be^(-1.82t))+39.9 I'm unsure how to proceed
5. ### Solar Heat Gain Factor table for southern latitudes

Hello! Despite being a mechanical engineer I'm fairly new to building science. I'm looking to compute for solar heat gains in a building somewhere down south. ASHRAE SHGF tables only lists data for north latitudes and there's no mention of the south latitude. May I ask why there isn't any on the...
6. ### B Describing the cooling of a room without any electrical or mechanical devices

Hello. I ask nothing here from a long time ago. One of my students is doing research on how to cool the air in a room without using any electrical or mechanical devices. For example: using just ice. What we need is how to solve/describe the process using math. For example: how to use/solve the...
7. ### I Superconductivity energy saved v Cooling/Heating energy loss

Hi! In reading about Superconductivity and its current state of only being achieved in super cooled or heated materials. This sparked a question the following question: What is the result of the trade off between energy saved by avoiding dissipation through the natural resistance of a material...
8. ### A ##\Lambda##-enhanced gray molasses cooling

Hello! I am confused about ##\Lambda##-enhanced gray molasses cooling. I understand that it combines gray molasses cooling with velocity-selective coherent population trapping (VSCPT). But I can't seem to understand what is the difference between these 3 methods. As far as I can tell, the main...
9. ### A Clear night sky radiative cooling -- How to optimize?

hi guys: what should be the colour of the collector for best cooling effect of night clear sky radiative cooling?
10. ### Finding an application where an air/n-octane mixture is cooled

For now, I just searched online for some kind of application relevant to the problem posed
11. ### I How to use cold air mass flow to support supermarket cooling?

An air mass flow of approx. 120 kg/h is available, which can or should be heated up from 0 °C to up to 150 °C. The cooling circuit based on propane R290 is to support the cooling of a supermarket. I have the load curve of the power consumption of the supermarket refrigeration to cool food at a...
12. ### I Effective Emission Height Calculation?

This is a climate change calculation question. AGW (Anthropocentric Global Warming) theory states that as a gas gets more dense, the height at which it will release IR (Infrared Radiation) to outer space gets higher. Higher in the Atmosphere is cooler. Cooler means a lower IR output. Reduced...
13. ### I have a few questions about refrigeration and AC units

I have a few questions about how fridge and AC work, i didn't know where to open this thread, i hope this is ok. So from what i learned so far, both work in a similar way, effectively moving heat from place #1 to place #2, in effect, "cooling" #1 and heating #2. The main difference (apart from...
14. ### I Mechanism of action of cooling from fans with misters

II'm trying to figure how adding misters to a fan, sprayed or nebulized water into the stream of air, yields increased cooling. Is it due to a non evaporative mechanism, perhaps better heat transport away from the person through humidified air versus dry air? It seems to me that the minimal to...
15. ### Chemical/Paint Best transparent material that allows infrared to pass through?

Trying to create a version of mass producible radiative cooling panels At first I want to start off with something able to be created at home relatively cheaply as I dive further in I will start trying to find more durable materials with the same capabilities In order for the system to work the...
16. ### Uncertainty in Newton's law of cooling

I'm finding the uncertainty of k, given that each temperature has an uncertainty of +/- 0.5 degress.
17. ### Possible to change a thermistor resistance curve?

Currently when set to 1C, the fridge cools to and maintains 4-5C(As a conversion when set to 34f it cools and maintains approx. 40f. ), all functions like fan/defrost are working correctly. Potentially the main board has an issue but all other zones are working correctly so I would prefer to not...
18. ### B Cooling liquid in rigid container

Hello, I have a sealed and rigid container, (can't change volume, can allow heat through), 1.0m x 1.0m x 1.0m in size, that is completely full with warm water, let's say at 40°C. The initial pressure in the container is 1atm and the volume of the water at 40°C perfectly matches the volume of the...
19. ### Cooling Water in Hard Soil: Data and Questions

Here’s the data is can supply. Water temperature entering ~51°C. desired water exit temperature ~38-40°C Water flow ~approx. 300L/min. Pipe Inside Dia.- 51mm Pipe Material- HDPE PN16 We would bury the pipe around 1 meter deep. Deeper is not feasible as the trenches would be hand dug in an area...
20. ### Heat exchanged in Expanding and cooling gas

For part(b), My solution is, ##\Delta E_{int} = Q - W = \frac{3}{2}(P_fV_f - P_iV_i)## ##Q = W + \frac{3}{2}(P_fV_f - P_iV_i)## ##Q = 4000 + \frac{3}{2}((1 \times 10^6)(6 \times 10^{-3}) - (3 \times 10^6)(2 \times 10^{-3})## ##Q = 4000 J## However, according to the solution b. ##−4000 J## Can...
21. ### COMSOL: Simulation of liquid nitrogen cooling (Help please)

The InSb sample (parameters 10x10x0.5 mm) is glued with silver glue to a cooled copper table. Liquid nitrogen passes through the table. While the model is at a temperature of 300 K and at a normal pressure of 1 bar. The sample is affected by a beam of electrons, which causes the surface to heat...
22. ### Rate of cooling of aluminum parts after a glycol heat process

I work for an aerospace supplier across different departments. I was recently shown how the production workers straighten aluminum parts after a glycol heat solutionizing process. The aluminum parts undergo a heat treatment for a few hours and are quenched in glycol. I can't get too in-depth...
23. ### Laser cooling of Earth's climate

Hi, I am worried about climate change. I want to cool the earth. Would it work to build solar panels to provide shade, and then to blast the captured light energy out into space via lasers? I think only certain frequencies will go through the ozone. Could solar powered lasers help cool the...
24. ### I Required kW for cooling and dehumidification + reheating

Dear all, First of all I would like to thank everyone for this great forum. I've been reading the forum for years, but I hadn't registered until today. My registration on this forum obviously has a reason. I have an issue that I can't quite figure out. I am trying to calculate how much power I...
25. ### How does evaporation generate cooling? Swamp coolers edition

I looked for other related threads and read through them, but I didn't find one where I could add replies, so I made another one. This issue came to my mind as I'm thinking about the benefits and detriments of swamp coolers given a hot climate and moderate to high relative humidity. 1) Some...
26. ### A Too much cooling air? (Power supply failures due to condensation)

I have a situation that I cannot explain so I need the assistance of someone with a good understanding of thermodynamics. I have 36 AC to DC power supplies located in an equipment rack. These power supplies are failing after some time. The failures appear to be moisture related. We put...
27. ### Heat Transfer & Cooling Capacity

Hi, zero education on heat transfer here, need some help. I have an electronics module that generates 15 W of electrical power over a 70mm x 20mm x 15mm heat load volume (aluminum). The ambient temperature is 25° C, the maximum temperature the heat sink can be is 40° C (ΔT = 15° C). Does...
28. ### I Heat transfer via air cooling -- which airflow direction is best?

I'm using a stainless steel pan and a fan to cool my coffee down as quickly as possible. Usually, I have the fan blowing down towards the coffee, but this morning I flipped it over to suck the heat out of the coffee and I'm wondering which of the two is the most efficient, especially as, in the...
29. ### B Opening this jar is made easier by cooling or heating?

I've found this question online and don't agree with the explanation given. Explanation I disagree. If you heat the jar, the diameter of the top opening increases more than the diameter of the wooden lid, making it looser. The opposite happen if you cool the jar and the lid. Can you please...
30. ### Answer the question about time of cooling of a ball

Hello, I'm not sure if this is the right place to post my question, however I still want to know. Recently, my teacher asked me the following question: "In which of the cases will the cooling time be the least: 1. the ball is suspended from the ceiling 2.the ball lies on a stand with a thermal...
31. ### Cooling of a thick walled pipe transporting water

Hi everyone, I'm trying to solve the following problem but can't quite get my head around it. I have a pipe of length, L (m), diameter, d (m), the pipe walls are thick (multiple meters). I know the inflow temperature of the pipe, say, Tin (K), and the pipe's external wall temperature, Tw. I...
32. ### How to calculate water pressure drop in cooling tower piping system?

When calculating water pressure drop in chilled water pipisystem (closed circuit) we always use Hazen Williams equation as follow:- but in case of calculating water pressure drop in cooling tower piping system (open circuit), shall we modify something in Hazen Williams equation or shall we use...
33. ### I Calculating Cooling Effect in Gas Cylinder Expansion

I'm building a gas supply system that will dump half the contents of a compressed gas cylinder of nitrogen in 10 minutes. I need to ensure the output delivery pressure doesn't fall below a certain limit because of cooling during the gas expansion. If the cooling effect is excessive, I will...
34. ### What is the Proof for Newton's Law of Cooling Formula Using Quadratic Equation?

I have went about this problem many different ways but cannot seem to come up with the answer. I am essentially trying to prove the formula provided in the ss of the problem.Could someone help me and tell me if I am approaching this wrong?
35. ### What is the Cooling Time for Steel Tubes with Ambient Nitrogen Gas Flow?

I am working on a new application and am trying to figure out how I can calculate the cooling rate of Steel. I have a load of Steel Tubes. 1200lb total mass. Tubes have some variance on size depending on what is being run on a given day, but nominally, we are looking at 1" OD x .1875" Wall x...
36. ### I Passive radiative cooling of surfaces below ambient air temperature

Apparently, it's possible to cool surfaces below ambient air temperature by passive (no input of energy required) radiative cooling to harvest water from the atmosphere: https://www.science.org/doi/10.1126/sciadv.abf3978 There's also a Nature paper about this effect, but behind a paywall...
37. ### I How does the cooling effect of this "white-est paint" work?

A new result from Purdue https://www.purdue.edu/newsroom/releases/2021/Q2/the-whitest-paint-is-here-and-its-the-coolest.-literally..html Is about the development of a new paint that is the whitest yet, reflecting 98.1% of solar radiation. That is so much that they claim that it causes a...
38. ### Cooling a marine engine while testing

For my internship I have to test and certify a Marine diesel engine. We are trying to run a few tests in our workshop, but this obviously means we can't use the sea or a river as cooling. We bought an IBC tank, which can hold a 1000 liters of water. The water from the tank will be running...
39. ### Cooling tower -- hot and cold water tanks

Hi In some projects, I saw that hot and cold water tanks have been used for open circuit cooling towers. What is the need to use these tanks?
40. ### B Cooling the room with a ceiling fan and skylight window

Hello, So I know that a ceiling fan either operate clockwise (winter mode) or counter-clockwise (summer mode) and while the fan is meant for just moving air around, I'm wondering if utilizing a ceiling fan and an opened skylight window only a few feet near the ceiling fan would help move the...
41. ### I Vibrational cooling of a molecule

Hello! I understand that many of the non-optical methods used to cool down degrees of freedom in a molecule (e.g. buffer gas cooling, supersonic expansion) are able to cool down translational and rotational, but not vibrational motion. Is this because the gap between vibrational levels is much...
42. ### I Laser cooling in a Penning trap

Hello! I tried to find some papers about laser cooling in Penning traps, but all I could find were theoretical papers, no experimental ones. Has laser cooling been done in a Penning trap? And if no, why so? I assume that sending the lasers is more complicated than in a Paul trap, but there are...
43. ### Thermal Physics: Computer cooling

Hello folks, I have a bit of a time sensitive question, if anyone happens to read this soon. A computer box consumes 80W power constantly. Outside temperature T= 290 Kelvin. Ambient pressure 10^5. If all the heat generated is expelled at 5 litres per second, estimate the inside...
44. ### Cooling things in water vs air

Hi everyone After I've cooked beans in a pressure cooker, I put the cooker (with beans inside) into a sink full of water to help it cool down. After a while, the water heats up. At this point, would the cooker cool faster if I left it in the sink or if I took it out again? I'm guessing it...
45. ### How can evaporative cooling air conditioning work?

If evaporative cooling (Such as sweating) is due to the escape of the hottest molecules into the air thereby lowering the total average temperature of the water then that means that that hot water molecule has gone into the air and has made the air hotter, so then how does evaporative cooling...
46. ### Classical What is the physical intuition behind radiative heating and cooling?

I am looking for a reference that will give me some physical intuition into radiative heating and cooling. I am not afraid of math, but I am not interested in performing detailed calculations.
47. ### What is the BTU load for a chiller to maintain a water bath temperature of 34 F?

I have been wracking my head about this one... In other jobs I have sized chillers a few times but this one is a bit different. We have a "Bath" of water, about 400 Gallons The baths beginning temperature is 34 F 5000 lbs of product runs through this bath every hour at a temp of 40 F Roughly...
48. ### Radiative cooling time derivation (for ambient temperature = 0 °K)

as T_∞ = 0 , I use Q=−F\epsilon A\sigma T^4 for this problem as the integration is much easier, so we start with mcdTdt=−F\epsilon A\sigma T^4 rearrange so T is on one side and t is on the other: −mcF\epsilon A\sigma T^4dT=dt on the left side I integrate from the initial temperature (Ti)...
49. ### B Why expansion of a gas implies cooling?

Normally expansion implies colding, but I don't know how to explain this with the equation of perfect gazes : ##PV=nRT## If V increase then the pressure diminishes. Admitting a constant number of molecules, is the number of shocks is inversely proportional to the volume ? But this only implies...
50. ### I Cooling Time for Air Conditioning

Please advise for cooling time on air conditioning. I have a project and customer asked me to make a comparison between their requirement and my proposal. And here's the result. Let's say that we provide a room with same capacity as above, function, delta T, load on that room, but ONLY air...