Questions tagged [cooling]

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Would water flow in the following system? [closed]

Would water flow in the following system?
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Newton's law of cooling , divergence of heatflux

The thermal diffusion eq is according to my book, Where J is heat flux, C is heat capacity per unit volume. The, to the Newton's cooling law, and what I don't understand here is, the first eq part ...
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Why can't we do this to reach absolute zero?

I have seen the argument that one cannot reach absolute zero in a finite number of steps. For instance on Wikipedia, it states It is impossible by any procedure, no matter how idealized, to reduce ...
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What determines the black hole accretion rate?

There is clearly a natural timescale to accrete matter around a black hole given by the balance of pressure and gravity, known as the Eddington luminosity. However, as I understand it, this is really ...
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Isochoric gas process taking heat from surrounding environment

this is a $pV$-diagram of Stirling cooler: A => B and C => D processes are isothermal, co temperature in D is same as temperature after cooling on high temperature side. Although, temperature ...
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How long does it take, and how much heat, to raise the temperature of air in a box?

I am seeking to crudely model a house with a window as a perfectly insulated box with a hole (which only allows radiative heat). My question is to find how the temperature of air in the box changes ...
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Does it make sense to discuss entropy change at different time frames?

The classic cup of tea cooling problem, why does it not violate the 2nd law of thermodynamics. The classic answer would be that the increase in the entropy of the surrounding is greater than the ...
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Is their any convention for measuring cooling in a material?

Im dealing with laser heating and cooling, in this area you have a lengths that are accepted measures such as an absorption depth and Diffusion length. https://www.pveducation.org/pvcdrom/pn-...
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Why is my max heat transfer lower than the actual heat transfer value (NTU-method)? Heat exchanger effectiveness is greater than 1 [closed]

I am using the NTU-method to calculate the effectiveness of a heat exchanger. The fluids are water (cold) and ethylene (hot). So far I got: $$ C_h = c_{p,h} \cdot m_h = 42.9\frac{kJ}{kgK} \cdot 44.4\...
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Help regarding discovery question in Thermodynamics

new to the forum and I'm currently learning about "heat capacity" in my physics book, and I've had a bit of a tough time trying to see the reasoning behind a certain question. In this book, ...
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How can this dimensional analysis of cooling rate account for a fixed ice cube volume

This Wikipedia article describes an analysis of the dependence of the cooling rate of an ice cube in water on the cube edge length, $L$. It claims that Buckingham's $\pi$ theorem predicts a cooling ...
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Calculate steady state temperature of an object heated by electromagnetic radiation

I would like to calculate the steady state temperature of a small cube of any material heated by electromagnetic radiation. Suppose the cube floats in air and doesn't touch anything. The air is at 20 °...
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Are microdroplets as good or better than liquids as coolants?

Well, I don't understand much about physics and such, so I hope I don't make too many misconceptions. So, from what I heard, gases in general aren't as good coolants as liquids because they aren't ...
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What exactly is a "sideband", when it comes to sideband cooling?

I am learning about the cooling and trapping of ions, and have come across sideband cooling. I can't seem to wrap my head around what a sideband, or more specifically, a sideband transition, is. ...
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Calculating heat loss to environment while an object is being heated up using Newton's Law of Cooling

I was experimenting with Newton's Law of Cooling lately, and I was wondering, how would one go about calculating heat loss to environment, while an object is being actively heated? Let's say I had a ...
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Can ionized air be used to create airflow without fans or other moving parts?

If I understand it correctly, ionized air should produce an electromagnetic field, which should mean that it can be attracted/reppeled by another field of the oposite/same charge respectively. If so, ...
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What does a refrigeration cycle do in a heat pump?

As we know, the refrigeration is the reverse of heat pump. They are both two different cycle where one is used for cooling and other is for heating. I dont understand, how can we integrate the ...
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Does magnetism affect thermal conductivity of metals?

If you're going to answer my question I'm sort of asking for some examples or a good graph that shows how it affects different metals if at all. I'm aware that it affects ferro fluid. I've seen mixed ...
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What is the difference between saturated and unsaturated photoassociation?

I was reading two papers and I came across saturated and unsaturated photoassociation. These papers are DOI: 10.1103/PhysRevA.66.063406 and DOI: 10.1103/RevModPhys.78.483. I am not an expert in laser ...
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Why i feel cool when near a lot of trees although it absorb heat from environment still it make environment humid ALSO? [duplicate]

Why I feel cool in a region with lot of trees inspite of humidity by transporation? Today I went for a walk and entered a region with lot of trees, It feel a sudden chill, a cool feeling (...
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Laser cooling of a trapped ion

I have Ca+ ion trapped at $z = 0$ in a harmonic trap. According to C. Foot's "Atomic Physics" the force on ion can be expressed as: $$ F=-\kappa(z-z_0)-\alpha v, $$ when it's cooled from one ...
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Does water become cooler when temperature increase so rate of evaporation increase?

We say rate of evaporation increase with increase in temperature either surrounding or of liquid! Does increased rate of evaporation due to increase in temperature cause increase in cooling? Because ...
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$\rm CO_2$ Pressure Enthalpy Diagram In Programming

Im trying to make a 1D model of $\rm CO_2$ cooling in Python. What I'm currently stuck on is programmatically reading a PH diagram. I have a bottle of $\rm CO_2$, which is vented to the atmosphere via ...
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2 votes
1 answer
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Can a laser-pumped laser cavity be laser-cooled by its pumping laser (and pump its pumping laser in return)? Is remote-cooling possible outside a lab?

tl;dr: Can one laser "suck" heat from another one (e.g. via Doppler-cooling, but not limited to that) hence remote-cooling it? I haven't found any non-paywalled literature on the ...
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Why isn't water thermal capacity used to easly cool the air in a room?

Why isn't water thermal capacity used to easly cool the air in a room? Would it be energetically cheap to use cold water as a room air cooler and when the water temperature reaches some limit it is ...
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2 answers
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How do we cool exactly as sweat evaporates from our skins?

We all know that when our sweat evaporates to the air we feel colder, but since this process is a latent heat transfer our body temperature will not change, then if our body temperature is constant ...
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How can it be shown that a system's entropy is reduced by cooling it?

I have a question on an issue that already bothers me for a longer time now. In quantum computing, one criterion that should be fulfilled is that an ensemble of qubits can be initialized in a low-...
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Air conditioner cooling capacity vs air flow rate and output air temperature

I have a Sinclair AMC-15A portable single-unit air conditioner. It's specifications state the following: Cooling power: 4.4kW Inside air flow rate: 420m3/h (max.) This seemingly defies (my ...
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How to calculate cooling time for copper billet after forging operation?

Presently we are heating copper billet to 740 deg. celsius and forging it in a Hydraulic press. Temperature after forging is noted at 700 deg. celsius. Room temperature is noted at 15 deg. celsius. ...
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Peltier, measure cooling effiency

I am wondering how to calculate the cooling efficiency of a Peltier device by having plots of the evolution of temperature of both side. Anyone has any idea?
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2 votes
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Cube cooling Fourier series coefficients

I wanted to solve a heat equation for cube which has initial temperature of $100°C $ and is cooling to the temperature of $20°C$. I calculated heat equation and I wanted get the coefficients $a_{n,m,l}...
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Could this imaginary cooling solution work?

Imagine a perfectly insulated ideal closed cylinder. Inside, at the two ends there are two bodies, one with the temperature of T the other with temperature -T. Between the almost touching bodies with ...
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Why is the rate of energy conducted in a rod equals the rate of energy released from the surface at the other end?

Assuming energy is released as convection only,we always do questions by equalizing, $$P_{\text{conducting}} = Q/t = KA (T1 - T2)/L = eA(dT).$$ Assume the system is at Steady State. Why does this ...
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Doppler cooling Ethanol

Is it possible to use laser cooling to cool Ethanol in it's gas phase? I've seen research on IR diode cooling when you reverse the electrodes but laser cooling was/has always been limited to atoms and ...
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1 answer
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Is my modification of Newtons Law of Cooling an infraction?

I'm working on temperature prediction and therefore also cooling. I stumbled upon Newton's Law of Cooling (NLC) and I do like its simplicity, but I'm not so happy about the condition that the ...
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Why does steam exiting a pressure cooker valve feel cool to the touch?

I made the surprising discovery that steam escaping a pressure cooker through a screw-valve on top of the pot feels relatively cool: I can comfortably place my hand on the steam without getting burnt....
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Accuracy of Newton's law of cooling

I've made an experiment to verify Newtn's law of cooling, but while doing the analysis, my results don't fit accurately with the data collected (303 data using a sensor). According with my initial ...
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1 vote
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Thermoelectric cooler's Qmax cites maximum heat transfer — how is it so close to rated wattage considering TEC's low efficiency?

Some background regarding my question: I'm thinking if making some sort of TEC-based ice cream maker. Considering the combined specific heat capacities, I calculated (possibly incorrectly) the value ...
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Is it possible to cool down air with warm water?

Is there some condition in wich the water evaporation can cool down the air even if the water is hotter than the air?
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Why is it hard to cool a mini-PC to room temperature?

I have this passively cooled mini-PC that froze every few days. After a lot of investigation I realized that it was overheating (running android studio and such) so I bought a fan, an arduino nano and ...
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Heat dissipation in space - how do they do that?

Consider a space aircraft. During its propulsion, I believe a lot of heat is transmitted to the aircraft by simple contact with the motor. But in space, there is no air to cool the aircraft. The only ...
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Can cooled gasses be bubbled up through water to cool it?

I'm working with a pressure vessel that is cooled to a reasonably cool temperature. Since it is cooled at pressure when the air exits the pressurized system the gas expands and thus cools a great deal ...
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8 votes
4 answers
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Energy-optimal beer cooling

Suppose that I am going to host a big party one month from now, and I have various liters of cold beverages that will need to be refrigerated by the time of the party. I have a fridge at home (which ...
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3 votes
1 answer
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What is the Festina Lente Regime?

I am studying BEC formation without evaporative cooling, so realized only thrpugh optical means. One of the problems to face is "photon reabsorption": an atom absorbs a photon of the laser ...
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1 vote
1 answer
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Air conditioner on rainy day [closed]

I got a new LG 1.5 ton AC(Air conditioner) . It's summer time here and the temperature reaches approx 40 degree Celsius at peak time. And it's working quite satisfactorily. But in the last two weeks ...
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1 answer
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Can a fan in a room cool down objects?

Does a fan cool objects? I have a ceiling fan in my office which really helps to keeps the room cool. Does it also cool down vitamins in a plastic bottle with a screw on top? My office can get very ...
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Initial and final pressures for the Joule-Kelvin expansion?

The Joule-Kelvin (or Joule-Thomson) expansion is an isenthalpic expansion in which the reduction of a gas' pressure from $ P_{i} $ to $ P_{f} $ results in a change in Temperature. It results in ...
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Temperature drop along silicone tube

I would like to ask your help to calculate the temperature drop of a fluid (at a specific conductivity) that flows in a silicone tube at different rates. This is a real case and I expect to perform ...
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3 votes
2 answers
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Open window in hot room, how fast will temperature equalize? [closed]

I am currently sitting in a warm room. I just opened a window to the outdoors, where it is cooler. Middle school science says the warm air should move toward the cool air, which should (in theory) ...
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1 answer
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Will a consumer freezer survive air travel with a pressurization/depressurization cycle?

Is it possible to ship a consumer freezer by air cargo (such as this one: https://www.danby.com/products/freezers/dcf072a2wp/ )? Or will the refrigerant gas expand too much and break the freezer? We ...
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