Heat transfer Definition and 947 Threads

Hi folks, Just a few general questions I have here. 1) The situation: A cubic block is taken from an oven and suspended so that both its top and bottom surfaces are exposed to the room air. Would the rate of heat transfer from the top surface be greater, equal to, or less than the rate of...

Suppose I have an object with a surface area of 2 square meters at a temperature which causes it to radiate energy at a rate of 1 kw per square meter. It has a very large thermal mass and so for the purposes of this experiment, a constant temperature . Around this object I have a system of...

Homework Statement Hi all, I have this problem statement with variables: 20" Diameter, 2000mm (length, L) cylindrical container with 8mm thickness made of plastic Container 3/4 filled with gasoline. Question: What is the immediately surrounding temperature required outside the container to...

A straight, uniform circular pipe of internal diameter of 88.43 mm and external diameter of 118.38 mm carries hot water at 63.67 deg cel. The pipe has a thermal conductivity of 247 Wm^-1 K^-1. how to calculate the steady-state rate of heat transfer per unit length, in W m^-1, when the outside...

Homework Statement Having trouble with code as seen by the gaps left where it asks me to add things like the coefficient matrices. Any Numerical Conduction MATLAB wizzes out there? A long square bar with cross-sectional dimensions of 30 mm x 30 mm has a specied temperature on each side, The...

i prepared a setup wherein i heat a nichrome wire with 3 volts battery, measure its power, the temperature of the nichrome and the temperature of air.. by using the formula ΔT=PRsurf where ΔT=Tnichrome - Tair P=VI Rsurf=1/hA, R is, basically, the thermal resistance to heat...

I'm trying to calculate the heat loss of efficiency due to increasing the mixture of propylene glycol in a heat transfer fluid compared to water.. For this I'm saying that water has a heat transfer efficiency of 100% (relative only) Im looking for multiple data points to create an equation...

Hi, I have a device which is heated from inside by constant heat (let's say by Joule's heat - UIt). Some heat causes temperature rise of the device, some is lost into surroundings through device's surface. I measured how temperature of the device varies with time and I want to calculate...

Homework Statement The temperature at the bottom of a pond of depth L IS 4°C. The temperature of the air , just above the layer of ice frozen at the pond surface is -2°C. THE THERMAL CONDUCTIVITY OF ICE IS THREE TIMES THAT OF WATER The thickness(X) of the frozen layer of ice must be-...

The temperature at the bottom of a pond of depth L IS 4°C. The temperature of the air , just above the layer of ice frozen at the pond surface is -2°C. THE THERMAL CONDUCTIVITY OF ICE IS THREE TIMES THAT OF WATER The thickness of the frozen layer of ice must be-

Hey, how would I start solving the total radiation transmitted through one plate, an air gap then another plate (double glazing) as well as the total convective heat transfer across the two plates? Thanks!

Homework Statement A solid body X of heat capacity C is kept in an atmosphere whose temperature is 300K. At t=0 temperature of X is 400K. It cools according to Newton's Law of cooling. At time t1 its temperature is found to be 350 K . At this time,the body X is connected to a large box Y...

I am trying to measure the heat transfer from a sealant curing oven. My methods were to measure the surface temperatures of the inside and outside of the oven with 4 T-type thermocouples as well as the wattage supplied to the oven via a wattnode. The curing process is typically a 2 hour...

I'm a game developer and I have an idea to make something heat up and cool off and I would like to use realistic style formulas to do the math. Instead of making it add dramatically over time. I basically need a formula for adding and removing heat from a 2 dimensional vector based on...

Hi all, I have a unique problem that I need some direction on. I have a .5x.5x.75 meter adiabatic chamber. No heat loss from chamber walls to the atmosphere. Inside the chamber there is an electrical flat heater plate .5x.05 meter with constant 100W. A fan blows air over the heater bar at...

Knowing the heat transfer rate q, how long does it take to lower a fluid from temperature T0 to Tf? This is for convective heat transfer from a heated body submerged in a fluid. I'm looking for an appropriate formula (google isn't helping) Thanks!

So this isn't a homework problem persay, it was given information but I just couldn't wrap my head on why this was true. We have 1-d heat transfer through a planar slab. If we have a T_a for the temperature outside, then as we T_1 for the temperature on one end of the surface, and T_2 for the...

Homework Statement Consider a brick wall, 4.0 m high, 6.0 m wide and 300 mm thick, where the thermal conductivity of the brick is 0.8 W.m-1.K-1. During a particular one-hour period, the temperatures of the inner and outer surfaces were measured to be T1 14oC and T2 6oC respectively. The...

I'm hoping to start a simple heat transfer model. It's basically a cylinder filled with air at a temperature T=300K. The bottom wall of the cylinder, made of steel, is heated (and kept at the constant temperature of T=400K). The side walls and top for the moment are treated as adiabatic (since I...

Homework Statement << Oversize image deleted by Moderator >> From this problem statement I am to find the heat transferred to the oxygen stream and the hydrogen stream. Homework Equations q''_0 = q''_oxygen + q"_hydrogen The Attempt at a Solution I first drew a thermal...

Im working on a little project where I am attempting to generate steam from a hot gas pipe. I haven't measured the rate of flow or temperature of the fluid as of yet, and I haven't decided upon the choice of material, but I'm looking for some calculations to start. My plan is to wrap a water...

Assume that there is a original wall which does not have any defect inside. After an excitation of heat at one side of the wall, Ti is 37°C and To is 30° C. Thermal capacitance is assume 1. So the heat transfer is 7. For another condition, i want to find out if the wall has air pocket inside...

Hi There. I'm currently working on a design project for school. Basically its a plate chiller which is lowered into a pot of hot liquid. The plates have channels in them thru which water will flow, the result being cooling of the hot liquid in the pot. I've done a lot of research and...

You place 1.0 kg of ice ( at 0 deg c) in a pot and heat t until the ice melts and the water boils off, making steam. How much heat must you apply to achieve this? Also, a printing plate of 20 kg is made of lead. After casting, the solid lead cools to 90 deg c . It is then dropped into a...

hi I am new here a query about heat transfer- there are layered walls with different conduction coefficient. the last layer is maintained at freezing point while the first is at room temperature my question is will the ice not melt at the last layer considering that its temperature is...

Hey, I was doing some revison for a test and i came across this question which I can't get my head around a clyndrical copper block, 0.3m in diameter and 0.4m long is initially at a uniform temp of 60°C and half its curved surface is exposed to a heat flux of 450w/m^2. If the complete surface...

I am trying to construct a portable personal cooling device. I am considering using tygon tubing and propylene glycol/water mixture as the coolant in the tubing circulating it through an ice water bath. The tubing would be connected to copper pipes, that would run into the bag containing the ice...

Homework Statement A fire fighter (approximated by a two-sided black surface at 310 K 180 cm long and 40 cm wide) is facing a large fire at a distance of 10 m (approximated by a semi-infinite black surface at 1500 K). Ground and sky are at 0 °C (and may also be approximated as black). What...

I need help regarding a small project on thermoelectric refrigerator. I need to cool a 5.4 ltr capacity refrigerating space to maintain it at 10-12 degrees. I have the cooling module in place.I needed to dissipate 98 W of power from one module via a heat sink. I have a heat sink that is of...

hello I need help regarding a small project on thermoelectric refrigerator. I need to cool a 5.4 ltr capacity refrigerating space to maintain it at 10-12 degrees. I have the cooling module in place.I needed to dissipate 98 W of power from one module via a heat sink. I have a heat sink that...

Hello, I'm not actually asking a homework question. I'm working at an internship and have been asked a practical question about how long it will take a steel rod to change temperatures. Homework Statement Because it's not a problem from a textbook, I may not have all the required data, but...

Alright, chemistry student here. No previous experience with these types of problems. Doing an interdisciplinary student project where we have to insulate a thin aluminum wall. http://i.imgur.com/8ztNq.gif We have a x=5mm thin aluminium wall used for dividing two air flows. T1=308 K and...

Homework Statement When an immersion glass thermometer is used to measure the temperature of a liquid, the temperature reading will be affected by an error due to heat transfer between the liquid and the thermometer. Suppose you want to measure the temperature of 10 mL of water in a Pyrex...

Homework Statement A copper rod of length 0.20 m and cross-sectional area 6.00 10-2 cm2 is connected to an iron rod with the same cross section and length 0.28 m (the figure below). One end of the copper is immersed in boiling water and the other end is at the junction with the iron. If the...

I tried searching for this but i couldn't find an answer so i hope this is hasn't been discussed and if so - sorry- and id appreciate a link.. Here we go: Lets say we have to glasses, A and B. In glass A we pour boiling water and add milk straight afterwards. Now for glass B we pour the...

Homework Statement A resistance, connected to a battery, is put inside a thermally insulated cylinder which has an adjusted frictionless piston and contains an ideal gas. Through the resistance, a current i = 240 mA flows. At which velocity v should the piston move upwards, so that the...

If an area of 1 m2 at the Earth surface emits Q/t = 54E-3 J/s in radiation, what would the temperature at the Earth surface be, if there would be no other energy sources? Assume that the Earth is a perfect black body emitter (e = 1). Q/t = e(5.67E-8)(A)T4 54E-3 = 1(5.67E-8)T4 T = 31.2 K? The...

Hello I am trying to validate my model by comparing a simple axisymetric 2D impacting flow of air on a surface. The geometry is simple: a cylindrical (diameter d=26.5e-3[m]) jet of air (debit Speed Ud=13.46[m/s]) is impacting a surface at distance H=0.2833[m]. Flow temp is Tj=20°C Wall...

Question: In an adibatic Spray cooler, a fine mist of liquid water is used to cool hot air by evaporating all of the water. The liquid flows in at a rate of 90 g/s and 30°C. The input hot air is at 450°C and 900 torr. The dewpoint of the input air is 47°C and the flow rate is 1362 L/s...

Hello, I have a little problem I'm thinking about for work. We are considering a design that moves heat across a contact interface between 2 heat exchangers, each made of copper, in a high vacuum environment. There will be one fixed heat exchanger, maintained at 25 C by coolant flow. This...

Howdy all, I am developing a high altitude weather balloon project and I am thinking of using HDPE as a lens material for THz optics. I need to know the total heat transfer on the sheet of HDPE to see if it will reach critical temperatures. Since I am only looking for critical temperatures I...

I need help, hope somebody can give me a hint Determine the appropiate orifice sizes for uniform exit temperatures of 140F from the four units in 70F ambient/ sea level pressure? Components (50W, 500W, 1000W and 300W) Thank you

Homework Statement The attempt at a solution The correct approach is to apply the lumped capacitance method. However, in the lumped capacitance problems I've faced before, it never had a heat generation as it does in this problem. How do I go about solving this?

I have two different scenarios for heat transfer I need some help with understanding. 1.) Given two different materials in perfect contact with each other with no thermal resistance at the interface, what are the interface conditions at the interface? Considering two heat equations with...

Hi, I need to model heat transfer in a 3D digital environment. I have very little physics / engineering background so I have no idea what's available or what software / methods are used. I have some background in CAD and general experience in Matlab, but this is going to be a steep learning...

Homework Statement Homework Equations Governing Equation : \frac{1}{r^2} \frac{d}{dr} (kr^2\frac{dT}{dr}) + q''' = 0 Temperature: T(r) = -\frac{q'''}{6k}r^{2} - \frac{C_1}{r} + C_2 The Attempt at a Solution For part a) all I did was multiply the equation provided in the...

hi, if i have a cylindrical rod of copper and i heat is at one end face while the other surface areas are open to the atmosphere then besides the conductivity of copper i will also need the convective heat transfer coefficient to analyse the setup. my question is : how do can we estimate...

Hi guys This is my first post here. I studied physics about 15 years ago and some weeks ago I realized that I'd forgotten most of it. So these days I'm playing around with physics just for the fun of it. So, I got to the subject of heat transfer, and though I would like to learn some more...

Homework Statement Consider a large plane wall of thickness L = 0.4m, thermal conductivity k = 1.8W/(m*K), and surface area A = 30m2. The left side of the wall is maintained at a constant temperature of T1 = 90 C while the right side looses heat by convection to the surrounding air at Ts = 25...

Homework Statement Two students, A and B, are discussing a heat transfer problem regarding what the surface temperature of a cartridge electrical heater would be when exposed to a water flow (CASE 1) and an air flow (CASE 2). Case 1: hw = 5000 W / (m2 * K); Tsurr = 20ºC Case 2...