Heat transfer Definition and 875 Threads

Homework Statement How much water remains unfrozen after 50.2kJ is transferred as heat from 260g of liquid water initially at its freezing point? Homework Equations The Attempt at a Solution

Hello, everyone, I have a question on how to calculate the heat transfer and change in temperature for a project I am working on. It consists simply of a cooling water block (that you would find on a tec cooler etc), a fresnel lens, and a pump. The fresnel lens focuses the light onto...

Someone a while back posted a link to a thermally conductive/heat transfer pad. Can't remember the details, but I remember I was intrigued by it...anyone remember what it was? [yes, I know this is vague]

I need some help estimating the heat transfer of a system. If I have an exposed length of pipe with a dynamic fluid moving at a constant volumetric rate through a very hot room, what equation is most appropriate to calculate the exit temperature of the fluid? Given: Initial temperature of...

Air with temperature of 80 F is forced with a speed of 30 m/s through a copper tube with length of 1 meter and inner diameter of 2 millimeters. The copper tube has a temperature of -50 F. I want the air coming out of the tube to have a temperature of less than 0 F. Is my design enough or does...

i have a system consists of a shell an tube exchanger and a centrifugal blower the blower suction is at the exit of the exchanger i want to replace the shell and tube with a multi plates heat exchanger whats my conditions for this process BLOWER 0.03 m^3/s max press 16 bar and SHELL...

I'm working on a project where I have to construct a cubic box, then find the heat transfer coefficient through the box. I will be placing various object in the box to run tests on how they change the eat transfer coefficient. If I want to use the equation: Q=h*A*delta-T, how do I find Q, the...

I'm working on a project where I have to construct a cubic box, then find the heat transfer coefficient through the box. I will be placing various object in the box to run tests on how they change the eat transfer coefficient. If I want to use the equation: Q=h*A*delta-T, how do I find Q, the...

Hello. People always say that the space is 'cold', and I've always heared that on a satellite, the side facing the sun is really hot, while the dark side is very cold. What I don't understand is how can the dark side be cold if the heat it had couldn't escape in any way except radiation, which...

Insulation as I know it, prevents heat transfer, and that's how a beverage cooler works to keep things cold right? I was wondering if it worked the same way in the opposite situation: do coolers keep things from freezing under freezing conditions? To be honest, I'm actually wondering if...

I am trying to understand how heat is lost from a glass aquarium tank maintained at some temperature above ambient. If we imagine a direct interface between the body of water and the surrounding air, I think heat transfer would be entirely due to radiation and convection. When a glass pane is...

Considering an engine generating thermal heat at 140 kw and when the generation starts the thermal equilibrium of the engine will be distrubed , a radiator is installed to cool the engine this radiator cool the engine through flow of water and water is cooled inside a heat exchanger with air ...

Hello, I was wondering: \frac{dQ}{dt} = \sigma A T^{4} for a perfect blackbody. Also Q = mc\DeltaT If I take the time derivative of the above equation, set it equal to the power emitted by a blackbody, and solve the resulting differential equation for temperature, does that give me the...

Homework Statement if the temperature of an object changes from 80 to 433 degrees Celsius, but the area and emissivity remains constant, by how much does radiated power increase? Homework Equations P=phi*A*e*T^4 The Attempt at a Solution i tried to do this: 80^4-433^4. and get the...

Hi Tell me some good books on machine design and heat transfer. What about Machine design by Norton?

Hi, I am currently faced with a problem. I am trying to design a cooling system that uses Geo-Thermal energy to cool water. From my research I have found that 12 feet below the Earth in the month of August the temperature is maintained at approximately 62-65 degrees Fahrenheit. I would...

Hi so i have a heat transfer project to determine the material (aka the thermal conductivity) and length of a 2d wall. It has to have between -1 and 1 net rate of heat loss from the southern side and above 145 rate of heat transfer from the eastern side. The wall is 20 cm high na the boundry...

Homework Statement Hello everyone I am studying for my finals and this question has me stumped. The ends of a cylindrical steel rod are maintained at two different temperatures. The rod conducts heat from one end to the other at a rate of 10 cal/s. At what rate would a steel rod twice as...

Homework Statement I've been given a Heat transfer problem, which I must solve in Matlab. The code should output the results and a graph of the temperature variation within the wall. Also the code needs to be able to run and output these results without any further user...

Hi, I wanted to ask, which type of heat transfer is generally most important for the transportation of heat especially at high temperatures? Does anybody know this? I am talking about temperatures T>1000 K

Homework Statement a furnace wall has an area of 3m^2. a thickness of 250mm and a thermal conductivity of 1.5 W m^-1 K^-1. calculate the rate of heat transfer through it when the temperature is 40K Homework Equations Q/t=KxAx(T2-T1)/LThe Attempt at a Solution This isn't homework as such, it...

I'm trying to explain heat and electromagnetic radiation to a group of middle school age kids. Would it be appropriate to describe heat as light that our eyes may not be able to "see" due to its wavelength, but that the nerves in our skin can percieve it as an incrased teperature? I'm looking...

Homework Statement An 85kg yachtsman falls out of his boat into the cold ocean waters. He begins to loose body heat through a 0.02m thick layer of surface fat. The surface heat transfer coefficient between his skin and the sea water is 30. The total surface area of the yachtsman is 2.2 and...

Hi. If there are two objects A and B, the temperature of A is TA, the temperature of B is TB, and my questions are: 1). If TA = TB, their internal energy (which is the kinetic energy plus some other forms of energy) might not be the same. In this case, A and B are in thermal contact. Since TA...

I am trying to predict the temperature of water coming out of a pipe. I know the temperature of the water going into the pipe. I know the material and characterisitics of the pipe. I know the ambient air temperature. I have explored Fourier's Heat Conduction \mbox {\Huge Q= $\frac {2...

I been debating this and figured you guys would know what the truth is. When you take the thermostat out of a vehicle, the flow is so high because of the thermostat not being a restriction, that the temperature gauge will hardly budge from whatever the lowest degree is, and if it does, it takes...

Homework Statement Consider two identical Einstein solids. One solid has been placed in boiling water and the other in ice water. Then the two solids are placed in good contact with each other within an insulated box. Using the concept of entropy, prove that heat will spontaneously transfer...

I got a question says "how much heat is requeired to change 3kg of ice at -9C to steam at atmospheric pressure?" I must do step my step the energy of each step (energy needs to heat ice to 0,energy need to change ice to water, heat water at 100 and then make water to steam) am going to find...

Homework Statement Two large thin aluminum plates, the first polished (emittance = 0.05 and the second painted black, are placed horizontally outdoors, where they are cooled by air at 283K. The heat transfer coefficient is 5 W/m^2-K on both the top and bottom. The top is irradiated with 750...

Anyone can tell me what is kinetics energy that needs to be convert into heat energy by the brake?( I mean can show me the formula or any journal) Anyone know any relevant heat transfer formula needs to be applied in order to determine appropriate sizes and surface area for the brake in...

Hello Please see the attached illustration, hope it gives a idea of what is going on. If I do not include radiation and the cylinder is infinite thin, how can I calculate this situation: (1) The water flow is constant inlet=outlet and steady state flow. (2) First there is not a heat source in...

Two bodies of masses m1 and m2 and specific heat capacities s1and s2 are connected by a rod of length L crossectional area A,thermal conductivty K and negligible heat capacity.The whole system is thermally insulated.At time t=0 the temperature of the first body is T1and the temperature of second...

Homework Statement A high temperature, gas cooled nuclear reactor consists of a composite cylindrical wall for which a thorium fuel element (Ka=57 W/m*K) is encased in graphite (Kb= 3 W/m*K) and gaseous helium flows through an annular coolant channel. Consider conditions for which the helium...

I have a heat source inside a steel box. I know the outside ambient air temp and the amount of heat the source puts of. How do I calculate the internal air temp of the box?

Homework Statement A flow of air at 27C and 1 atm is hydrodynamically fully developed in a 1c I.D pipe with uav=2m/s. Plot(to scale) Tw,Tb, qw as a function of the distance x after Tw is changed or qw is imposed. a) in the case for which Tw=68.4 C = constant b) in the case for which qw=378...

Hi, I'm not sure if I've got this in the right section, but I'm hoping someone can point me in the right direction. I'm trying to create a model of what's actually happening during the combustion cycle in an engine and where the energy is going. As the intake valve closes and the piston...

Homework Statement One dimensional system in vertical direction 2 meter high composting pile @ 65 \circC Top of pile has wind @ 40 \circC and h = 50 W/m2*K Bottom of pile at ground temperature of 20 \circC Only conductive heat transfer WITHIN pile; no convection Volumetric biochemical heat...

Hi Anyone with experience with transient heat transfer please can you help me. I have attached an image that is a simple stirling engine schematic. One half is essentially a pipe that is heated from one end and kept at room temperature at the other end. Inside it is a displacer that is not...

Greetings All, I am a PhD student in a physical chemistry department. Our research group would like to build our own high termperature ovens for preparing samples. Nothing fancy, just a controlled rise in temperature to a given setpoint, hold it there for a designated amount of time and the...

1. The problem statement A truncated cone 30cm high is made of Aluminum. The dia at the top is 7.5cm, and 12.5cm at the bottom. The lower surface is maintained at 93 deg C, the upper surface at 540 deg C. the other surface is insulated. Assuming 1 dimensional heat flow, calculate the rate of...

I am working to build a device that includes an air pump and heater. The pump will push air through a tube at the end of which will be a heater element. After doing some research, it seems that Nichrome is the standard heating wire for hobbies. I'm planning to have the heater in a glass-section...

Hi. I am not in any way proficient in thermodynamics, but I was thinking about insulation and heat transfer and a few questions occurred to me. Since insulation blocks heat transfer, shouldn't a winter coat block heat in a hot climate? If you could only choose between wearing almost nothing...

I am digging back thorugh thermodynamics textbooks, and am seeing insulation values etc. but none on how to solve for time required to heat a material. Here is the specific problem. I am trying to fgure out how long its takes to cool (or alternately heat) a concrete slab. The slab is 8...

URGENT: Heat transfer - temperature gradient value at a certain point Homework Statement Given a very long cylinder of inner R1 = 0,01 m, outer radius R2 = 0,1 m, that transports water at 150ºC, and surrounded by air at 25ºC, find the temperature gradient value at R = 0,07m. \lambda = 500...

Hi guys. Without going into too much detail. Basically I have a counter-flow heat exchanger problem where I need to find one of the outlets temps only given the inlet temps of each fluid. I have no idea how to do it though as I'm not given a value for over heat transfer coefficient (U) or...

Homework Statement How much energy is required to change a 46.0 g ice cube from ice at -10.0°C to steam at 116°C? Homework Equations specific heat c = Q/(m(Tf-Ti)) Q = cm(Tf-Ti) latent heat Q = mL The Attempt at a Solution 2.05*10*46+4.1813*100*46+2.080*16*46 +...

Looking for people interested in this topic for discussions and probable scientific cooperation

Lets say a hot object is at 500K and placed in a chamber with wall temperature of 300K. The surrounding air in the chamber is 320K. So what is the mode of heat transfer for the hot objection? There is convection and radiation. so the heat transfer rate, q = q(conv) + q(rad), right...

Homework Statement A rod with length L and section A has its extremities in contact with 2 springs of heat whose temperatures are T_A and T_B such that T_A>T_B. The rod is an environment where the temperature is worth T_0 (constantly). a)Determine the function T(x) that describes the...

What is the efficiency of induction heating? What if you only had 8800 Watts available, or perhaps 220V, 40Amp... what size iron object could you heat, and to what temperature? Size will have to be qualified... how long? What shape & how thick? Depth of heat penetration. Then how long would it...