Cooling Definition and 646 Threads

I have an application where I need to calculate the vacuum (pressure change below atmospheric) generated from a cooling liquid in a semi-rigid container. If the container is filled near full (e.g. 2 litres) with a liquid at e.g. 70C, sealed and left to cool to ambient (e.g. 20C) there is a...

When going through topics on melting and freezing, i came across 2 graphs of slightly different curvature for both the heating and cooling of naphthalene. The ending part of the graphs are the ones that confuse me, whether slope upwards or downwards. Most graphs in the internet just show...

Homework Statement A thermometer is removed from a room where the air temperature is 20degree C and is taken outside where the temp is -10degree C. After 1 minute the thermometer reading is 3degree C. What is its reading after 3 minutes? Homework Equations The Attempt at a Solution...

Homework Statement Hello i am doing a cooling experiment and i want to know the following: y=28.49e^(-0.03890*800) +26.51 (note the 26.51) is not part of the exponential. What is y? and I was wondering whether this would go ever go through the x axis? Thanks people! Homework...

A friend of mine brought his laptop to me today after it started acting funny, turned out to be over heating problem, since then and I'm thinking.. Why don't they make a cube/container and place the processor in it with liquid Nitrogen around it? Wouldn't that keep it cool forever? I'm not a...

I read it in my book that Newton's law of cooling can be derived from Stefan's law. Is it possible, and if so, how?

Newton's Law of Cooling (not the formal definition): (change in time) = -ln ((Tf - S)/(Ti - S)) / k Tf = final temperature Ti = initial temperature S = temperature of environment k = heat transfer coefficient Say that you wanted to cool something (such as a person) to a negative...

hello all, We live in a hot part of the world with the extra bonus of high humidity - around 90%. We don't have A/C, and don't really want to get it (energy use). Evaporative cooling won't do much (towel on head) becuase of water saturation in air. Would a cold wet towel + fan force water...

If you put a piece of very hot metal in cold water the heat in the metal will transfer to the water until both are the same temperature. So the system water-metal still has the same initial energy. So my question is how does the piece of metal cool if it is put on a perfect vacuum. Is it...

In the summer most of us turn on our air conditioning and we use lots of electricity in the process. But by cooling our home we're just taking heat out our homes. Heat is a form of energy. If we are taking heat away why are we also using electricity in the process? Can't we turn heat into...

Hello Everyone, I am Mayur I am working on a system, in the system there is one diffuser through which exhaust gases at 3000K are flowing at a rate of 170Kg/s. The material of diffuser is Stainless Steel. The diffuser is double walled type with cooling water flowing between the walls. I need...

Homework Statement A hot metal rod is placed in a water bath whose temperature is 40F. The rod cools from 300F to 200F in 1 minute. How long will it take for the rod to cool to 150F? Homework Equations The Attempt at a Solution I know y'=-k(y-T0) and y(t) = T0 + Ce^-kt and i...

ok racers, here is a subject I have been debating. our formula car uses two aluminum radiators, one on each side. I switched to the Ultra Side pods which are each 5 pounds lighter and 3 inches narrower than the original sets. Benefit is lighter weight and lower aero drag. now the questions, 1...

Advice needed please with the design of cooling vents, louvres on the cowling of a radial engine. Plane is a Sukhoi, as per vid links below, 76 inch span 37cc petrol engined radio control. Cooling will be from cutouts in the cowl approx 20 x 80 mm with a flat plate louvre at the leading edge...

Hi, I'm a cyclist who has just got some rollers, which allow me to ride inside without going anywhere - essential if I want to ride on harsh winter days. The problem is, without the cooling airflow normally experienced when out on the road, heat exhaustion makes long periods of indoor training...

Hi there, my first post on this forum and I hope its in the right place ! My question is this, in an exisitng air-cooled motorcycle engine what is the viability of using heat pipe technology to cool exhaust gas temperature? Using heat pipes to remove heat from exhaust valve areas to external...

Homework Statement Hi, I need some help in solving Newton's law of cooling problem. Use Newton’s law of cooling to determine the reading on a thermometer 5 min after it is taken from an oven at 72 ◦ C to the outdoors where the temperature is 20 ◦ C, if the reading dropped to 48 ◦ C after...

If we were able to build a gas core reactor, how much heat would need to be dissapated? I bring this up because traditional solid core reactors require lots of heat to be pumped away (do you know the exact number?) to keep the core for melting, but since a gas core is already much hotter...

Hi guys and gals :smile: I am currently working on a project that involves server cooling. My objective is to make some sort of (gross) generalization about what kind/size fans go into typical rack mounted servers. When all is said and done I would like to be able to categorize my findings in...

Homework Statement Suppose that a cup of hot coffee at a temperature of 1850 is set down to cool in a room where the temperature is kept at 700. What is the temperature of the coffee 10 minutes later? Homework Equations f(t)=(T0 - T1))e-kt + T1 where T0 is the initial temperature of the...

Homework Statement a body has temperature 27C at twelve oclock. The room temperature is constant at 16C. Two hours later the body was found to have a temperature of 24C. The temperature of a normal human body is 37C.Using Newton's law of cooling estimate the time of death. Homework...

I'm going to write this up the same way my teacher gave me the sheet Homework Statement At 9am on october 19, 2009 a body was found in room 327 at University Center. The room is kept at a constant temperature of 72 degrees. The medical examiner was called and he arrived in eight minutes...

I'm going to write this up the same way my teacher gave me the sheet Homework Statement At 9am on october 19, 2009 a body was found in room 327 at University Center. The room is kept at a constant temperature of 72 degrees. The medical examiner was called and he arrived in eight minutes...

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Hello all, I am doing a research which involves hollow copper conductors. I would like to know about some kind of coolant or gas (like SF6) which can be passed through the copper tube to cool it, the temperature of the copper conductor can reach upto 100 degree C. The coolant should cool the...

Hello all, I am doing a research which involves hollow copper conductors. I would like to know about some kind of coolant or gas (like SF6) which can be passed through the copper tube to cool it, the temperature of the copper conductor can reach upto 100 degree C. The coolant should...

Hi. I'm trying to apply Newton's cooling equation (if relevent) to the following system. We produce plastic piping, extruded at about 200 'C and cooled via water sprays to 35 'C. We are trying to calculate how fast we can run the pipe through the cooling sprays. It's been a very long time since...

Hi. I'm trying to apply Newton's cooling equation (if relevent) to the following system. We produce plastic piping, extruded at about 200 'C and cooled via water sprays to 35 'C. We are trying to calculate how fast we can run the pipe through the cooling sprays. It's been a very long time since...

Could I get a hundred feet of 3" corrugated drain pipe for the air and run it through a 6" corrugated drain pipe for running cooled evaporated water which would be pumped out of one end and gravity fed through the other end. As for the air "tube", I would run one end into the home at one...

Homework Statement The temperature, H, in degrees Celsius, of a hot cup of coffee placed on the kitchen counter is given by H=f(t), where t is in minutes since the coffee was put on the counter. Is f'(t) positive or negative? What are the units of f'(20)? What is its practical...

Homework Statement I have two problems. What is Delta U, Delta H, q, and w for the Reversible heating of an ideal gas at constant P. Also, what are these values for the Reversible cooling of an ideal gas at constant V. Homework Equations The Attempt at a Solution For the...

I am trying to solve an advanced heat transfer problem and I have a 2nd order ODE. I can solve the homogeneous solution easily, but I am having trouble with the non-homogeneous solution.Homework Statement Given a turbine blade and asked to model as a one-dimensional fin, subject to the...

Hi everyone, I have encountered a situation described as follows in my research and would appreciate it if someone could help me out - A ball of metal vapors ( Pressure = 10^10 Pa and T = 10^4 K) is suddenly exposed to He gas at 1 atm. I wanted to know how would the Temperature change due to...

Homework Statement A thermometer reading 70o F is placed in an oven preheated to a constant temperature. Through a glass window in the over door, an observer records that the thermometer reads 110o F after 1/2 minute and 145o F after 1 minute. How hot is the oven.Homework Equations...

http://www.ucar.edu/news/releases/2009/arctic2k.jsp The associated albedo flip will amplify the warming.

the diesel cooling engines as produced by deutz have huge fans to deliver substantial amounts of air to the engine. they draw a lot of power from the engine. is it possible to use a mesh of delaval valves like a radiator that drops the temperature of passing air, thus, reducing the amount of air...

Hi, in a lecture I was told that the cooling of neutron stars cannot happen via the 'direct' Urca process (beta decay and inverse beta decay), because the created particles cannot go into occupied states (Pauli exclusion). The 'modified' Urca process was introduced, with an additional neutron...

Homework Statement You are given 2.5 102 g of coffee (same specific heat as water) at 70.0°C. In order to cool this to 60.0°C, how much ice (at 0.0°C) must be added? Neglect heat content of the cup and heat exchanges with the surroundings. Homework Equations Q=(m ice)(c ice)(delta T...

I have a dough passing through a pair of rollers equipped with internal circulating chilled water. given: mass flow rate, specific heat and temp in/out of the product diameter of the rollers, its material. temp. in of the chilled water. problem: cooling load needed for the chiller.

I would like to determine how long it would take a volume of water to cool from an initial temperature to a final temperature in a given ambient temperature. I don't know the volume, is this information important? If so, is there any way to come up with the time it would take as a function of...

I have experimented the converse of Newton's law of cooling, i.e. the rate of heating of a cold body is directly proportional to the deficient temperature when the difference in temperatures is small and the states of the system remain the same.

Suppose the temperature in your room is 25 °C with 100% humidity. You are feeling very hot and sweating a lot. Most of the sweat does not evaporate on your body, it just drips onto the ground. If you switch on the heating in your room, would you feel more comnfortable? It seems to me that by...

Fusion raction produces high energy neutrons which cause activation of the walls of the reactor. Why can't their energy be collected by, for example, a microwave beam?

How much electricity does it take to liquify oxygen? I am just curious as if it only took small amounts one could create a power plant that liquified oxygen, put it in a small chamber outside to return it to a gas and used the pressure to turn a turbine with the gas returning for cooling. This...

Hello everyone :smile: I'm just wondering why is cooling considered to slow reactions. I mean f you want condensation heating would slow the reaction. I like to know exactly how condensation occur at molecular level. I know when you heat gas it expands. So when you cool a gas does it...

Is there a PDE describing temperature as a function of time for a sphere in a vacuum (a moon in space)? Since it can only radiate, the boundary would be a function of temperature to the fourth power (nonlinear), right? Is there a book or thread out there I can reference? Maybe this can...

I'm unsure how to approach this, as solid blocks of materials next to each other (e.g. steel and air) with no barrier inbetween as shown on http://en.wikipedia.org/wiki/Thermal_conductivity "x" would equal zero, this can't be correct. Is there another equation relating temperature difference...

I have the answers to these, but I have a question about them. The answers to 1 are P,P,M+P,M , and the answers to 2 are F+P,A+B+F+M+P,A+B+F+M,A+B+M,A+M . My question is, how come some of the answers to 2 have austenite, while none of the answers to 1 do? I don't see a Mfinish line...

The degrees of freedom associated with the possible orientations of the spins of the magnetic atoms constitute a spin system, which is in thermal interaction with the degrees of freedom of translational motion of all the atoms which constitute the lattice system. If the external magnetic...

Newton's Law of Cooling Time Required to Cool (or heat) an Object [Also known as Newton's Law of Cooling] t=mCp(Ts-Tf)/Q Where; Q is the heat added (or being removed) from the object in watts m is the mass (weight) of the object in Kg Cp is the Specific heat of the object...