Heat transfer Definition and 947 Threads

Homework Statement A 1.0 cm diameter steel rod with k = 20W/(m-K) is 20 cm long. It has one end maintained at 35°C and the other at 100°C. It is exposed to convection heat transfer with h=65W/(m^2-K) and an ambient air stream at 20°C. a) Sketch the distribution of temp within the rod. b)...

Hello Everyone, The question I am about to pose concerns something I may possibly already have an answer; however, I would like to proceed with posing the query, that I might solidify my understanding. If a system transfers heat to its environment, does this necessarily imply that the...

Homework Statement Homework Equations d/dx(kdT/dx) + S = 0 (for steady state) q_cond = -kAdT/dx q_gen = S*Vol The Attempt at a Solution So I tried to equate q_cond to q_gen but it seemed to give me the wrong answer. Does anyone know why? I believe to get the right answer I have...

By oversimplifying the problem I have, imagine that I have a panel constructed of stainless steel flat walls. The dimensions are 80 in x 70 in x 20 in, and the thickness of the panel is 1/8 in. Inside, I have a heater that outputs 400W of convective heat. The temperature inside the panel is...

Homework Statement I am curious about the situation of heat transfer between parallel horizontal plates in an enclosed space (particularly with the lower plate being higher temperature and subjected to a steady heat flux) with the enclosure itself being composed of a fictional "perfect...

Here is the solution to the problem, all you need to look at is the diagram, the conductivity values and the graph. What I don't get is why the temperature is not continuous when the material changes. Shouldn't there be equilibrium at the boundaries between the different materials?

Homework Statement Homework Equations (unsure) The Attempt at a Solution Homework Statement Homework Equations The Attempt at a Solution

What is the difference between constant wall heat flux and constant wall temperature for convective heat transfer correlations?

how to reduce temperature of a solid bar from 550°c to 450°c by water spaying... someone really help me...??

Suppose you have a cylindrical rocket engine with surface temperature T and you want to measure temperature on the inner wall T0 of the combustion chamber (assume 1 dimensional heat transfer). The chamber has thickness d, and heat transfer coefficient k. If combustion is assumed to occur...

so I'm told that temperature difference is ultimately what results in heat transfer. But when considering what happens inside a uniform material, if temperature difference was solely responsible for heat transfer, then different heat transfer rates wouldn't exist among different materials at the...

I was hoping someone could lend a hand with a question about thermodynamics. It's been years since I've done work on thermodynamics. Let's say I have a plastic 275 gallon liquid container, filled with a mixture of Propylene Glycol and Water (50/50 by volume). The container is placed inside of...

Homework Statement What mass of water at 25dC (d = degrees) must be allowed to come to thermal equalibrium with a 1.85kg cube of aluminum initially at 1.5*10*2dC to lower the temperature of the aluminum to 65dC? Assume the water doesn't turn to steam. Homework Equations Q = Del(T)m(C)...

Homework Statement The world's most active volcanos, such as the Kilauea volcano in Hawaii, can disgorge about 5 ✕ 105 m3 of 1000°C lava per day. What is the rate of heat transfer out of the Earth by convection if this lava has a density of 2800 kg/m3 and eventually cools to 32°C? Assume that...

Hello. I'm a student of Univ. of Korea. As you can see in the attachment, I'm calculating the Temp variation in 2-D. The node 24 has a convection from left upper quadrant with h, a conduction from right upper with k1 and a conduction from bottoms with k2. I can't figure out how should I...

Have a new task, would appreciate some pointers. Conducting a heat transfer analysis on a tank with water coming in and out that's to serve as a hot side for a displacing stirling engine. If the inlet q dot into the tank is 1000W. Observing there will be losses due to conduction and...

Homework Statement Homework Equations The Attempt at a Solution I am not sure about the relevant equations to be used here. At first sight, I thought I had to apply Stefan's law but then, the question states the power consumed by bulb, not the radiated one. I am completely...

Homework Statement What is the expected temperature change during one second of a polypropylene solid with mass 0.1 g at 105 degC to air at 20 degCHomework Equations heat transfer: Q= c m (T1-T0) where Q = amount of heat c = specific heat capacity = 1.8 J/g/K m = mass T1-T0 = change in...

Homework Statement Derive a differential equation (do not solve) for the temperature distribution in a straight conical fin. Assume one dimensional heat flow. This equation is assumed to be 1-D steady state conduction. Homework Equations For this problem, we can use the generalized...

Hi Guys, can I get some advice on how do I get started on the question? I'm guessing that natural convection is the key to solving the question. but i have no idea on how to solve it.

Homework Statement Hey guys. I've been cracking whole day over this question to no avail. I mean I have no idea if it's correct or wrong. And I desperately have to get it done by tomorrow and it's already midnight here so would really appreciate any sort of help I can get. Here are the doubts...

Hey guys. I've been cracking whole day over this question to no avail. I mean I have no idea if it's correct or wrong. And I desperately have to get it done by tomorrow and it's already midnight here so would really appreciate any sort of help I can get. Here are the doubts that I'd like to...

I want to build a box that is warmed by sunlight. I was told that aluminum in the sun is much cooler than bare aluminum, both because it absorbs less light (even infrared?) and because it is a better black body radiator than bare aluminum. Is this correct? Ideally the surface toward the...

Homework Statement Sketched below is a solid, truncated cone, with a side profile of y=Cx. Based on the geometry, the area (in m2) of the left (truncated, x = 1m) and the right face of the cone is 4∏ and 36∏, respectively. The temperature of the left face is T1=50°C and T2=30°C. Assuming...

Hello everyone, I have this setady state, heat transfer problem; I hope you can help me with it. I have flux source of 400 W/m² (a lamp), and i want to calculate the heat flux passing through a surface arbitrarily placed and oriented in the space. There is air in between. How can i do this...

Homework Statement Hi guys, I don't really need help with answering the dollowing question but just have a quick question about it. I solved the first part of the question with an energy balance by letting q_{conduction} = q_{convection} to get the temperature of he outer...

Dear all, I am a bit stuck trying to find out how heat is transferred through an evaporator in a refrigerator. I was using Newton's law of cooling before I realized there are more complexities in the equation as the refrigerant is in a mixture of saturated liquid and saturated gas in the...

Dear all, I am a bit stuck trying to find out how heat is transferred through an evaporator in a refrigerator. I was using Newton's law of cooling before I realized there are more complexities in the equation as the refrigerant is in a mixture of saturated liquid and saturated gas in the...

I am not really a heat transfer guy so I hope someone here can help me out here. I would like to know the formula to get this. Here is what I ma facing: I have a mandrel (basically a piece of cylindrical H-11 steel). It has OD of 3.5 inches and 37” in length. It has a core hole of about...

Hey all, I'm trying to simulate a simple chip-heatsink situation in SolidWorks using their thermal modeling suite. I have found an ideal set of parametric values for the chip to work at a reasonable temperature, but I need to figure out what the convection coefficient means in terms of air flow...

Hi There Does anyone out there know a good estimate or any real values for the total heat transfer area for the hot and cold sides of a domestic refrigeration system? i.e. the sum of the areas of the evaporator and the condenser. For the Evaporator: QL=UL.AL.(TL-T1) AL=heat transfer...

I am setting up a system where a rectangular plate is heated by a set of heater cartridges, producing about 4000 watts. This plate is in free convection air. It is used to melt plastic at regular invervals. I am trying to model the system so we can estimate temperatures of the plate to...

Homework Statement a) Liquid is stirred at constant volume inside a container with adiabatic walls. The liquid and container are regarded as the system. Is heat being transferred to the system? Is work being done on the system? b) Water inside a rigid cylindrical insulated tank is set into...

I have been tasked with calculating the cooling time of an extrduded steel rope running thru a water trough at a certain feet per minute speed. I've been researching conduction heat transfer equations and can't seem to find what I am looking for. I was oping someone could help me with the...

The heat transfer equation is Rate = k•A•(T1 - T2)/d where k is the heat transfer coefficient of the material. But I'm feeling that the other material transferring the heat should be important too. I mean if I were to touch Styrofoam at 50 degrees and metal at 50 degrees, the metal feels...

Hi people, I'm currently working on a project regarding entropy generation by (emissive only) radiative heat transfer from heat sinks. But I'm unable to find a proper treatment regarding Second Law analysis for Radiative Heat Transfer. Can someone give me the link to any book or any article...

Homework Statement Calculate the surface temperature of a stainless steel junction box that is in a 35C ambient temperature environment. There are electrical "boxes" that generate 30W of heat inside of this box. Homework Equations (1) Q_dot_total = Q_dot_conv + Q_dot_rad (2) Q_dot_conv...

Hi all, Doing some calculations on an air-cooled heat exchanger at the moment and could use some help understanding the variation of air-side heat transfer coefficient (htc) with flow rate. It's more of an intuitive problem really as I'm okay with the math, etc. So I know that as you...

I am currently in the process of designing a section of pipe in which a fluid will flow within, and would like to determine the specific heat transfer which may occur once the fluid enters the pipe, until it exits. The fluid will be flowing at a constant velocity "V" at a Temperature "T1" at...

ansys -- heat transfer within pipes and with surroundings hello , am doing my master in architecture n currently in my thesis stage and the thesis is about heat transfer within pipes and their influence on the surrounding atmosphere. i wish to know which is the right kind of analysis in...

what is the max free air heat transfer coefficient(film coefficient)? at 1000 c? i have a object that is at 1000 degree c by applying 900watt. i model it solid edge and apply heat generation load of 900 watt, from what i research air convection is 5-25 w/m^2/k. but when i apply that in the...

let say a cylinder(steel) is 6 cm diameter and length of 3.5 cm length. and is heated to 1000 degree c. in a room of free air and room temperature of 20. will convective heat transfer dominate? it radiation is negligible? what would the convective heat transfer be? what power(watt)...

whats would be typical value for free air convection heat transfer coefficient at high temperature of 1000 degree c? let say i have a vertical cylinder of diameter 5 cm and 3 cm high. and i heat it to 1000 degree c. the room temperature is 20c . what would the convection heat transfer...

Homework Statement Problem is in attachment pic. Homework Equations The Attempt at a Solution My attempt is on the pics 1 and 2. Firstly, is it valid to assume length as 0.075m? - For part (i), from the question it infers that one of the cylinders is applicable to the lumped...

hi, this is more of a biomedical engineering question but since it involves heat transfer i thought i would run it by the mechanicals... theres a cancer treatment called laser ablation and the dosage requirements are based on an understanding of how laser-light induced heat at a point source...

Homework Statement A 2kW immersion heater for heating water in a large tank is to be made from a straight horizontal sheathed element of diameter 10mm. A sheathed element is an electrical resistance wire embedded in magnesium oxide powder and enclosed in a stainless steel tube, (there will...

I've got a problem with calculating (estimating) how much heat is flowing out of a metal bar in the following system; it seems like it should be simple but I can't see where to go with it. System: A small metal bar with length l=2.5mm, width w=0.2mm, thickness t=0.2μm with resistance R is on...

Homework Statement A steel cylinder of diameter 8cm and length 12cm is initially at 600°C. It is placed in oil at 20°C for rapid cooling, for case hardening of the surface layer. The value of h is 60W/m2 K. Use the numerical method. a. Determine the time in which the maximum internal...

How can I determine the thermal conductivity of two different aerial coolers' tubes, taking into account the ambient temperature of the air? The overall goal is to determine which cooler is able to cool water the best, but the data was taken during different outside air temperatures. Below...

I would like eventually compute the battery duty cycle required to keep a high altitude balloon payload somewhat temperature controlled. On my last flight I failed the GPS tracker due to unknown cause (maybe CTE). At any rate the cold temperatures are not good for components, accelerometer...