Heat transfer Definition and 947 Threads

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...

Hi, I'm really struggling with a thermodynamics coursework question, I'm not looking for the answer straight up, just wondering how to go about solving the problem as it's been racking my brain for a stupid amount of time. Here's the problem I've been given: Shaft work (500kJ/kg) 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 to conserve heat energy in a home, R=2.8 Pink Batts are replaces by R=3.2 Pink Batts. calculate the percentage increase in reduction of heat loss per 1.0m^2 of wall when the temperature difference is 15degrees celsius. Homework Equations P=A(Th-Tc)/ R The Attempt...

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, Is somebody here a casting simulation engineer. I am in the processs of learning, the complete process of modelling it and am stuck with Interface heat transfer coefficient between the mold and the casting. I am using procast inverse method, but am having difficulty finding the solutions...

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...

Suppose we have a body (cube or sphere) at temperature T1. The surrounding area has a constant temperature T2 with T2<T1. We need to deliver the body at temperature T1 at some time in the future. There are two options: We can heat the body continuously at temperature T1 or we can allow the body...

Hai I have a problem with heat transfer coefficient estimation. Please help Here is the problem: Two experimental scenarios are compared. Case 1: I have a well defined rectangular area in a silicon wafer. Water is completely spread over it. The mass of water is known. Air is blown over...

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...

Hi, I am trying to model the heat transfer along a pipe using MATLAB as a transient problem. I understand matlab's ODE45 for one thing that is being solved for, but when something is broken up into lots of 'nodes' I do not understand how to get ODE45 to solve for them all. I have made a...

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...

Homework Statement The problem is about Nevada Solar One thermal solar power system.It uses 760 parabolic mirrors reflecting sunlight on a cylindrical tube carrying a heat transfer fluid.Each mirror contributes 84kW giving a total 64MW. Assumptions:The mirror has a width(orthogonal to...

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...

In July the Hanze University and the Rijks University Groningen participate in the Frisian Solar Challenge . This is world race for solar boats. The solar cells we use are so-called B50 cells with an efficiency of 21%. The cells perform worse if the temperature rises. The way we cool the...

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...

What I'm trying to figure out is the temperature vs. time of a aqueous nuclear reactor. I'm trying to cool 200kW of energy with metal pipes running through a working reactor. This is just a heat calc, I'm not actually building one. The reactor runs at 200kW, is liquid filled, and will be...