Heat transfer Definition and 947 Threads

If I had water at 180 degrees and dropped the temperature to 160 degrees over a heat exchanger, would I have the same BTU output as if I had water at 100 degrees and dropped the temp to 80 degrees? Delta T is 20 degrees for both situations. I know if we were talking about Ke related to mass and...

Hi, I'm interested in the theory of an Aluminum sphere that is initially at some temperature that is hotter than its surroundings. The sphere is surrounded by air at some small radius, say one meter, and then the air and sphere are both enclosed by an infinite shell of Aluminum at some...

In a heat transfer with internal heat generation what does the term "internal heat generation" mean? Is that applicable only if a body itself produces some heat (Like current carrying wires,nuclear fuel rods etc) Or if i have a two cylinders one within another,and if inner cylinder is heated...

So, I know that it has been sort of asked in other forms before, but they mostly deal with human beings and so I've yet to find an answer to the specific part of this quandary: if a mechanical system is exposed to space (with just the skin of the ship itself as the only boundary between heat...

Homework Statement I have a general concept inquiry. I was doing some thermal homework, and calculating values of Q in a given cycle. One process was isothermal, however it turned out that Q was not zero, causing me to wonder: How can there be a heat transfer in an isothermal process...

Hey all, not sure if this is where I'm supposed to post this question, but it is all about heat transfer. So this is part of my design project for my 4th year of chemical engineering. Problem Statement: A hollow cylinder 400 m long has hot combustion gases T = 500 Celsius flowing through...

Homework Statement A small pond has a layer of ice 1cm thick floating on its surface. The air temperature is -10 C. Steps (a-c) should help you fi nd the final answers in (d) and (e) (a) What is the temperature of the liquid water just below the ice? (b) Write the expression for...

An insulated Thermos contains 122 g of water at 91°C. You put in a 13.7 g ice cube at 0°C to form a system of ice + original water. Use mc(ΔT) |water + mc(ΔT) |ice + Lm |ice = 0 Final T = [(m*c*T) |water + (m*c*T) |ice - (L*m) |ice] / [m*c |water + m*c |ice] Final T =...

Hello everybody, I am trying to figure out if a heated enclosures will effect my temperature readings from a temperature probe. As shown in the picture below, the arrow in the middle shows an enclosure 9"x7"x8" that has a 30 watt heater inside and a battery backup system 27"x 22" x 18" on the...

I have a quick question regarding the interrelationship between heat transfer and thermodynamics. Basically, since temperature as governed by the equations from the study of heat transfer, is neither uniformly distributed (a field) and changes with time (non-equilibrium), how applicable are...

I'm doing a steady-state thermal analysis for a cylinder geometry. Inside the cylinder is a heat source and this heat is going to water channel (modelled with FLUID116 elements) and the air. For air convection I have to define a heat transfer coefficient which is dependent on the flow of air...

I'm designing a vertical farm prototype and I'm trying to do some preliminary calculations to get an idea of how hot my crops are going to get. The basic design consists of a low-e glass (SHGC=.39) in the front and an aerogel panel in back(see attached diagram). I'm calculating for the hottest...

Homework Statement We are having a fictive, non existing heat exchanger with the following parameters: Outer tube diameters: 20 & 12 mm Wall thickness inner tube: 1mm, outer tube; 2 mm flow area hot side: 0.0226m2, cold side; 0.0272 m2 The heatexchanger is going to cool some hot...

Homework Statement ==================== <---- aluminium plate ⁣⁣⁣⁣⁣⁢⁢⁢⁠⁡⁡⁢⁢⁢...O .....O... <---- heat coil(O) Given an aluminium plate put on 2 heating coil(O), assuming no heat loss, how much is the heat transfer rate from the coil to the plate? Put the power of each coil as W...

Homework Statement A cube of Al (.1m x .1m x .1m with mass=.27kg) is placed on a large thermal mass maintained at constant 40 C (313 K).The cube is separated from the thermal mass by a .01m thick glass plate (.1m x .1m). If the Al block is initially at 10 C, how long does it take to reach a...

First off, I can't believe I never decided to search for a forum like this, I love smart people! lol. Anyways I am working on a Liquid cooling project for a highly overclocked computer system. Originally I wasn't going to use a heat exchanger(Matter of fact, until I stumbled across one on a...

Hey guys I really have difficulty learning heat transfer and I wish if someone knows a website that includes experiment or some kind of help. Thanks and I appreciate your time

Hi everyone I have a quick question regarding heat transfer. I have yet to study heat transfer yet but I have a basic understanding of the mechanisms from general physics courses. My particular question is regarding airflow across a surface and its ability to cool a heat source. The situation...

Hello everybody, I would like your comments on my findings and perhaps prompt me to look at relevant literature. Consider an enclosed airspace 1m length, 1m height, 0.5m width. At the center of its one 0.5 side a fan is drawing air out of the chamber through an aperture(steady, low air...

Homework Statement Determine the temperature of the filament of a 60watt lamp, if the filament has an area of 10mm^2 and an absorptivity of 0.35. Assume stefan-Boltzmann constant is 5.67*10^-8 W/(m.K^4). Homework Equations The Attempt at a Solution The equation I have attempted...

Homework Statement A silicon chip measuring 5mm by 6mm and of thickness 1mm is embedded in a ceramic substrate. At a steady state, the chip has an electrical power input of 0.3W. The top surface of the chip is exposed to a coolant whose temperature is 20°C. The heat transfer coefficient for...

does a cup of coffee, say 85 degrees C in a 20 degree C room, lose more heat due to radiation or conduction. In general, do common objects lose more heat due to radiation vs. conduction?

Why does the different in temperature between 2 body determine the rate of heat transfer? Why does the temperature gradient decrease as it reaches thermal equilibrium/fixed point of a substance? Apart from using the equation Rate of heat transfer = kA (Difference in temperature) / d How...

If we have a pipe with dimensions D=0.006m L=0.01m and a mass flow of m' = 0.019 kg/s How can we determine the heat transfer coefficient of the pipe?

Estimate how long a time it will take to cool a trailer filled with coke ? Given the ambient temperature is 22 degrees C and heat transfer provided by the refrigeration unit is 10 kW and the drinkable temperature is 4 degrees C. Make reasonable estimates of how much insulation is included on...

I have a quick question that maybe someone can help me out with. Let’s say I have an object that has a heat output of 48.7 KJ that is constant and it is surround by hydrogen that it flowing around it. Like a rock in a stream. If I know the starting temp of the hydrogen how would I determine how...

Homework Statement I don't really understand something in my textbook. It says the heat Resistor (how to say that in English? I hope it's alright like this...) trough a cylindrical tube (from the inside to the outside or revers) would be: R(heatrisistor)=1/2∏Lλ * ln (R1/R2) And then my...

Hi Guys, This is for my university project.I need to design a oil tank for the formula student car.The first stage is the analysis of the existing stock oil tank (Aprilia SXV 550 is the engine).I need to find out the heat lost/transferred from the of the existing oil tank.How can I calculate...

Hi Guys, This is for my university project.I need to design a oil tank for the formula student car.The first stage is the analysis of the existing stock oil tank (Aprilia SXV 550 is the engine).I need to find out the heat lost/transferred from the of the existing oil tank.How can I calculate...

I found the following: We have already seen that the flow of heat through conduction occurs when fast (hot) atoms collide with slow (cool) atoms, transferring some of their kinetic energy in the process. One might wonder why the fast atoms don't collide with the cool ones and subsequently speed...

Homework Statement A space station in outer space (far from the sun) has a total surface area of 580 m^2 with emissivity of .62. The temperature of the outside surface is 156 K. the walls are .25 m thick with an average thermal conductivity of .038 Wm^-1K^-1. Find the temperature of the inner...

Hello, My attic gets blazing hot in the summer days, i have installed more than enough electric fans, my house just never gets shaded and the attic is quite small. my first idea was to build a giant shade producing robot. after that, I decided to vent all of my A/C air into the attic...

A problem from a heat transfer book with conduction and radiation led me to a differential equation like this: T'(t) = a - b*T(t) - c*T(t)^4 Although my professor said that there wouldn't be an analytical solution for this one and to get the answer by an iterative method I got curious and...

Hi, I would like to know if somebody has the formulas to find the heat transfer coefficient while the nucleate boiling and the film boiling, for a plate heat exchanger... I really look forward reading someone. Thanks

A glass window 1m x 2m and .005m thick has thermal conductivity of 1.4W/m K. Inner surface temp of 15C and outside of -20C, what is the heat loss through the glass. double paned construction two panes separated by .01m, if glass surfaces are 10C and -15C, with air thermal conductivity of...

The graph is in the attachment! ( don't have to download to view the file)Homework Statement 49a) A 0.25 kg piece of ice is warmed by an electric heater and the following graph of temperature is produced. Assume that there has been no loss of energy to surroundings. How much additional time...

What is the *main* mechanism of heat transfer between a thermal resistance and water? My doubt arose in the context of a problem (from a high school national test) dealing with the following situation: a 500 W thermal resistance made of copper is immersed in a jar containing 500 g of water at...

Homework Statement determine the thermal effieincy of a heat transfer process where the following data has been used Input=3kW 1.7 litres of water have been heated from 313K to 375K in 2.5 minutes specific heat capacity of water= 4.19kj/kgK Homework Equations Thermal efficiency=...

Hi everyone! First time here, but I'm having trouble with a problem. Here goes: On a given day, heat losses through the 20cm-thick walls of a warehouse are 0.02 kW/m2 when the outside wall temperature is 5C and the inside wall temperature is 25C. The owner would like to reduce her heating...

Homework Statement where λ= thermal conductivity \dot{q}= dissipation rate per volume Homework Equations qx=-kA\frac{dT}{dx} The Attempt at a Solution I don't know where to start from to be honest, so any help would be greatly appreciated

Hello, I have 2 problems that are currently bothering me, and I would enjoy help with either. The more immediate of these problems is with my family's gas stove. Whenever we need water to boil, we put the pot on and turn the burner all the way up. My father then comes in and turns it...

I AM DOING A PROBLEM ABOUT TRANSIENT HEAT TRANSFER AND IT SAYS: "A solid sphere of steel has 1 cm of diameter and a initial temperature of T0 =15 ºC. It is placed into a flow of Tinf = 60 ºC where the convection heat coefficient is h = 2000 W/(m^2K): (Density of steel rho = 7832 Kg/m^3 ...

Dear all I got a value of 37 for h ( convection heat transfer ) Does it consider as free or natural convection heat transfer coefficient? Thanks in advance ! And Sorry its not a Homework problem :)

I am confused as to how heat transfer really works. I've read all about conduction/convection/radiation. Radiation makes sense to me, electrons enter a higher band, come back down and give off energy in the form of EM waves. These waves can then be absorbed by other atoms causing electrons to...

Homework Statement This is a lab report that I'm working on. I'm almost done, except for the last part which consists of finding the error in the result for our heat transfer coefficient h using Newton's law of cooling. I've tried this in different ways but I can't seem to get it right. We...

Hi guys, I have a question regarding heat transfer. When I have a piece of heated metal which is left to cool down in air, it goes something like this right? Heat is transferred to air by conduction (metal to air) then from air heat is given off by convection currents. Also, radiation occurs...

Homework Statement I am required to conduct a thermal shock test where by a stainless steel object (complicated geometry) is to go from one tank of light oil at -55°C to another tank of the same light oil at +140°C, then back the -55°C tank. This is to be repeated 5000 times. In order to...

I am looking to utilize flexible stainless steel corrugated tubing similar to this: http://www.pipesystems.com/site/index.cfm?id_art=24995&vsprache=EN as a heat exchanger immersed in a tank but have been having a tough time locating technical data on it other than the "surface area" and of...

Using heat transfer equation to find out heat transfer rate but reached a puzzling result, where did I do wrong? Problem statement: Heat transfer rate of a heated plastic plate in air, considering only one side, the size of the plate is 15cm X 15cm, assuming temperature difference is 1K...

Im trying to write a MATLAB code for 2d transient heat transfer. The problem is a titanium block in the shape of a rectangle is staring at a specified temperature and is being exposed to a much hotter surrounding temperature. The dimensions, coefficients of heat transfer, and temperatures are...