Cooling Definition and 646 Threads

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...

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...

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.

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...

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)...

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...

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...

Apparently the answer is to have the jumper over the bucket. Am I wrong in thinking that the jumper transfers heat to the ice cream, why does it not do so? A similar question elsewhere was "Colin claims to have built a refrigerator alternative which works without any power supply. It is a box...

First i calculated the latent heat of vaporation: h_vap(15°C)= 2465.4 kJ/kg In the next step i calculated how much water is already in the air: x=0.622*j*ps/(p-j*ps)=0.00988 kg/kg where: j=50% ps=0.03171 bar p=1.01325 bar Now that i know that i can calculate the enthalpy of humid air: h_hum =...

Hello friendly people of PF So I have a tank with about 250 litres of mineral oil in it. and computer servers are immersed in it. the oil keeps the servers cool but get's hot in return. What different (economic) ways are there to cool the oil down? The best way I could think of was Oil-water...

Neutron stars have surface temperatures of 1,000,000 degrees K. Yet they are not creating energy like a normal star. They are just cooling off. How long does it take for such a star to cool to room temperature, 300 degrees K.?

Hi, when modeling convective cooling in FEA one needs to define film coefficient ##h## and ambient temperature ##T_{amb}##. The software calculates convective heat flux using this data and current surface temperature ##T_s##: $$q=h(T_{s}-T_{amb})$$ However, modeling of moving cooling nozzle may...

Howdy all. Regarding the phenomenon of radiative night sky cooling, where an object (such as a blackbody) on the surface of the planet cools via radiating energy into space: can the cooling be ascribed to the transmittance of the radiation through the atmosphere (as such a clearer night with...

Hey guys. I have a room which i want to use as a server room. the devices need to work 24/7 and they get pretty hot. so it is imperative to keep the room cool otherwise the devices will be damaged. I have an air vent to bring cold air into the room for the devices so their fans can suck in cold...

I'm having quite a bit of a problem with this one. I've managed to figure out that ##T_0 = 0##. However, not knowing what ##q(t)## is bothers me, although it seems that I could theoretically solve the problem without knowing it. For ##t>t_1##, integration by parts gives me ##T = Ce^{-t/10}##...

This is a project that I wanted to do in the past 3 years, but I never was sure enough because I don't know how to calculate thermal transfer in a submerged coil to at least have an approximation of what to expect. I want a cheap solution to pass the summer days without cook myself or wasting a...

I converted dm3 to m3, all the degrees to kelvins and found out the specific heat constants of iron and aluminium (0,45 and 0,91 KJ/kg K), but now i am failing to understand how this was supposed to be calculated. The equation given doesn't really help, as there are two unknowns in it: Q and the...

Hi all, Consider the situation depicted in the illustration. Two identical 'square plates' are situated at rest, in frame S, as shown: Plate A has its thickness 'a' parallel to the x-axis and its sides 'L' parallel to the y and z axes, while plate B has its thickness parallel to the y-axis and...

Hi, recently I got interested with practical applications of Newton's law of cooling. Its main disadvantage is that one has to measure temperature at some point of time (other than ##t=0##) to obtain solution for any other ##t##. However I've found an online calculator...

Hi, First of all I am sorry if I post in an incorrect thread. I can ask my question in PC forums but I thought it probably better if I ask in physics forum. So, I am trying to make the temperature in my PC better by adding additional fans, however I can't really place the fans in whatever...

Currently there is an operation scenario at one of our plant which directly injecting steam into cooling water line at pump suction in order to generate hot water at 60 deg C for circulation, by doing this its generate vapor at pump suction and lead to cavitation which ultimately damage pump and...

Hi, I have been exploring Newtons Law of Cooling. What relationship should i expect to see from the cooling constant "k". I have plotted the "k" values for each equation that i have developed (based off of different volumes of water in the same sized beaker). So, when the "k" vs volume graph is...

In the process of developing a tank venting program and starting to investigate how to incorporate tank gas expansion cooling I realized that since: T=P/nR with R constant and the reduction of P and n directly proportional then this equation implies all tank ventings are isothermal. What am I...

In reference of Ned Mohan's book, I have designed a heatsink, firstly natural convection taken into account, but laboratory test results and theoretical calculations are not matching. The test results: For 40 A (means 62 W), 30 Celsius ambient temp, it raised up 51 Celsius. So, Rs-a =...

So I'm having trouble understanding the physics behind evaporative cooling. This is what I know: I want to cool some water so I nebulize it and I let an air flow (coming from the outside) pass through this mist of water. Now some water has to evaporate. Here I am stuck because I don't understand...

I am having trouble wrapping my head around a particular problem I am thinking about. Consider that I have a heating source that I can describe in terms of either degrees Celcius / second or Joules / second, but essentially I am able to determine a fixed heating rate. Let's say: dT/dt = 5...

I am not sure how to proceed. This is just something that i have been thinking about and would love a little help with. Lets say I have a situation where i am increasing an object's heat energy at some specific rate - for arguments sake, it's 2 degrees every second. If you like we can also...

I am currently trying to solve a problem for my dissertation. Help would be greatly appreciated. :) A silicon solar panel of area 1m^2 is being warmed by the sun. It achieves a constant temperature of 80 degrees celcius. I am trying to cool this panel which is constantly being provided solar...

Good day everybody! As we have already known the structure and operation of the cloud chamber, can someone explain to me why the cooling is done at the bottom of the chamber and the heating at the top, but not vise versa?? How this affect the function of the cloud chamber?

Homework Statement A metal ball of mass 1kg is heated by means of a 20W heater in a room at 20°C. The temperature of the ball becomes steady at 50°C. (a) Find the rate of loss of heat to the surrounding when the ball is at 50°C. fa) Assuming Newton's law of cooling, calculate the rate of loss...

MODERATOR'S NOTE: HOMEWORK INCORRECTLY POSTED TO CLASSICAL FORUM, SO NO TEMPLATE I need help with the following question: Please have a look at the question and my attempt at the solution. Alternative cooling systems are considered for a large computing centre requiring 1 MW of cooling...

Homework Statement Having chilled the air until it contains only the perfect amount of moisture, you want to reheat it to the ideal cabaret temperature. You could use an electric space heater or wood fire, but you already have another source of heat: the same system that chilled the air in the...

Homework Statement Why will operating ceiling fans during the winter improve the house's heating efficiency and reduce the heat flow between the ceiling just below the attic and the cold attic itself? a. Stirring air always makes it feel warm and helps prevent thermal conductivity. b...

I need to increase the surface area of the glass which will be used in a solar still with the intention of keeping the glass as cool as possible. My first thought was bubble wrap because it's transparent and I thought it would not interfere with the light but then I remembered it is a good...

Hello, I have a question regarding the derivation for Bose Einstein condensation. I understand that in a boson gas for high temperatures the expectation value of the total number of particles should equal something like: $$ \langle N \rangle \sim T * \eta(z)$$ With ## z = exp(\frac {\mu} {k_b...

Hi - I have been trying to figure out how long an object takes to cool and I am just banging my head on the desk. Info: Metal object is placed into an oven set to 302F (150C). The object is 3' long and 2.75" diameter, and is solid metal (steel). The object is "baked" in the oven for 30 minutes...

I am working on a project; a computer case made out of wood, most likely oak. I was wondering if two fans (one bringing air in, on taking air out) would be enough to keep the system at a stable temperature. I wasnt sure because i know most cases are made of thin metal which conducts and...

If I have a laboratory water bath (circulated for homogeneity in temp) that I will monitor over a period of time (probably 2 scenarios, an hour at most, and then at least 24 hours or longer), how do I quantify the effect of atmospheric pressure in our test lab. What I will do is use an...

*Given Newton's Cooling formula, where T(t) predicts temperature, and where Te is the temperature of the enviornment, T[0] is the temperature when t = 0: T(t) = Te + (T[0]+Te)e^-rt predict Te when T(120)= 86.632 T(240) = 79.210 r = 0.001 I don't know how to even remotely go about solving...

Hi, I have been trying to set up a funtcion of the temperature over time and I am doubting my results. In the system i have: Fig 1. The system is at rest. For simplicty I've considerd the ambient temperature to be same as T1. By knowing: Fig 2. yeilds: Fig 3. In my case B&C is at a...

Is there a cooling fan with a heat sink on the Smartphones CPU - Quadcore processor and above similar to the desktop and Server CPU? If not, why?. Is it not required? Thanks & Regards, Prashant S Akerkar

In the 19th century Lord Kelvin made the first numerical calculation of the age of the Earth not based on the Bible.From his initial guess that the Earth started as a molten rock and that today the temperature of the interior increases at a certain rate as you approach the center, he got an age...

This probe is designed to fly closer than 4 million miles from the sun's 'surface'. Is it possible in principle to cool the spacecraft 's inner facing surface by transferring heat to a cooler part and then radiating it into space from the far surface? I don't think it is equipped with such tech...

Hi There, Can anyone please help with the attached diagram of a cooling system? In particular the role of the compressor. I understand what happens at each stage but I am keen to understand why. The Hot Airflow passes the Flow Control Valve and some passes through the Primary Heat Exchanger...

When performing cooling load calculations of an hotel room, do I consider the toilet as part of the area being cooled as it is at negative pressure with respect to the room and cooled air will flow from the room into the toilet. Or should I perform and the load of the room separately and add...

Hello, I was tasked with calculating the cooling and heating load calculations for a hotel which employs passive chilled beam systems using HAP. Can someone please provide me with the highlights of the calculation procedure and things to watch out for, especially things that differ from load...

Hello folks, got a question regarding cooling tower I will like to understand. I got some performance data from some cooling tower makers on the condition of how the cooling tower will operate at different wet bulb temperature. Assumeing flow and fan power is constant, what i observe was the...

Hi I am is desperate need of advice, I live in sunny South Africa have 10 trout dams on an estate for catch and keep purposes. Each dam is approximately 2,5 Acres and 3 metres +/- 10FT deep in certain areas. The main issue is in summer the water temperature is sitting at 28deg celsius 82...

Dears Kindly, I want to hear from you regarding this topic. The system is closed cooling system. I believe it is difficult to attribute the sound you hear from centrifugal pump to be a cavitation especially if the discharge pressure is normal. The last time we had a problem with this system...

Hi, I have an underwater monitor housing made out of carbon fiber and an acryllic Glass on the other side. Over time the monitor heats up. I guess carbon fiber is a bad heat conductor :(. the Acryllic glass is almost 1cm thick. Does anybody have an advice on how to cool something like this...