Heat transfer Definition and 947 Threads

hi all i need guidance on how to solve this exercise. thank you all in advance

Homework Statement 1litre of water is heated by an electric burner which couples 500W into the water. How long will it take to raise the temperature of the water to boiling point? How much longer will it take for the water to evaporate?Homework Equations Δu=mCΔT, where The Attempt at a...

Hi, I am currently doing my final year project in college. I am using a copper pipe which is 8m long with 8.5mm ID and 10mm OD. The pipe is bent into a coil which will be placed inside a acrylic box. The aim is to pump water through the coil to get the box to a desired temperature. At the...

So I've been wondering this for a couple days now: Is radiation the only means for decreasing the internal energy of our atmosphere? I know that in kinetic theory the molecules are similar to bouncy balls and if they were in contact with the vacuum of space, the air molecules would have no...

Homework Statement A furnace wall is made up of 3 layers: 1. 4mm layer of material with thermal conductivity of 52 W/m.K 2. 2mm layer of material with thermal conductivity of 20 W/m.K 3. 1mm layer of material with thermal conductivity of 3 W/m.K There is an air gap between layers 1&2 with a...

I am trying to explain the convection heat transfer and the mass transfer related (buoyancy of the heated part of the gas) using only kinetic theory of gases , I mean using only collisions between molecules of the gas. The environment is the usual one : a hot wall in contact with a gas...

Hello guys, I have a problem and I don't know how to solve it properly ... So I have this situation: And I must calculate the heat transfer (Q) through it ... I know that the Indoor Temperature is 21C and the outdoor Temperature is 0C, I also know the following data for all layers...

I need recommendation about heat transfer book . I am having a difficult time learning the concepts. I've tried reading several dfiferent textbooks(e.g. Cengel, Kreith, Chris Long), and though they sometimtes state the same theorem using different wording, different arguments, etc, I am still...

Homework Statement A 0.8m high and 1.5m wide double pane window consisting of two 3mm thick layers of glass(k=0.78W/mK) is separated by a 10mm wide stagnant air space(k=0.026 W/mK). The convection heat transfer coefficients on the inner and outer surfaces of the window are 10W/m^2K and 35W/m^2K...

1. My Conceptual Questions (5) is at 3. CONSIDER: Case 1: two dissimilar slabs of material (say slab 1 and slab 2) connected in series (bonded at their interface). There is a temperature difference: T1 @ slab1 and T2 @ slab2. Case 2: two dissimilar slabs of material bonded together, i.e...

I have to design accumulator of energy. Let's consider insulated cylindrical tank with water. How to calculate all heat losses. Should i consider convection between water and wall and then conduction? but what with all sides of tank? It would be easier with single wall. how to get all...

Homework Statement Two identical brass plates, each 0.5 cm thick, are separated by a rubber spacer of thickness 0.1 cm which has the same cross sectional area. If the outer surfaces of the brass plates are kept at 0 °C and 100 °C respectively, calculate the temperature at each side of the...

I recently installed a water solar heating system for my pool. The pool is 16,000 gallons and the current temperature is 54 degrees. I can get water through the system at 65 degrees at 10 gallons per minute, or slow it down and produce 2 gallons per minute at 80 degrees. Assuming no...

Hi, I'll describe my problem more specific. I have a continuous flow of this polymer thread (polystyrene) at 465 °K (190°C sorry I'm metric) that needs cooling down. It passes trough a water bath which is kept at 310°K (35°C). Now i try to calculate the heat exchange into the water, to...

Hi all! I am trying to solve a system of partial differential equations in Matlab, with both derivatives in time and space domains. I am using the pdepe function for that. The system is, to be simple, a sort of solar thermal panel, made of three layers: an absorber plate, a fluid layer of...

Homework Statement Is my approach correct? Thanks all :) a)The specific heat capacity of water is 4200Jkg-1K-1 while the specific latent heat of steam is 2.26x106Jkg-1. Explain what is meant by the statement in italics. b) Explain, in terms of molecular motion, the large difference between...

Homework Statement Three building materials, plasterboard [k = 0.30 J/(s m Co)], brick [k = 0.60 J/(s m Co)], and wood [k = 0.10 J/(s m Co)], are sandwiched together (as I've tried to show below). The temperatures at the inside and outside surfaces are 28.9°C and 0°C, respectively. Each...

Hi all. I'm doing a heat and mass transfer whereby I'm supposed to come up with a relevant daily life example and do a 2 pg report on it. I have kind of decided to do on popcorn popping via convection. So basically from my web research the popcorn kernel contains about 13% moisture and the...

Hello. I am completely new to MATLAB and programming in general. I never thought I would have to resort to online help, but here I am. I have spent hours googling and haven't been able to get very far. 1. Homework Statement Calculate the distribution of the temperature of the inner part of the...

Homework Statement With the time rate of change for heat transfer: dQ/dt = kA(dT/dx) k = thermal conductivity constant A = boundary surface area dT/dx = temp gradient Homework Equations Can the solution for Q(t) be obtained from modifying Newtons Law of Cooling since dQ/dt is proportional to...

Homework Statement Consider a person in a room with an air temperature of 21C. The persons core body temperature is 37C and their surface tissue thickness is 5 mm. If the total surface area of their skin is 1.5 m2, and they are wearing clothes of a thickness of 2 mm and the surface heat...

When modelling the heat transfer through a plate using fouriers equation, what difference would it make if the width and length of the plate were set to a specified value rather than being infinite?

Homework Statement A circular floor 9.15 m in diameter has an emissivity of 0.8 and is at a temperature of 29.4C. The floor is enclosed by a hemispherical metal dome which has an emissivity of 0.1. If the net rate of heat transfer between the floor and the dome is 660 W, calculate the...

I am setting up a hydraulic system on a cable laying machine. We don't have much space for the tank, and I am thinking of constructing it on the "wall" og a big 1m^3 stainless steel sand holder. That would make the tank With 5 faces in open air, 1 face With sand on the opposite side. I am...

I am running a simulation on a flat plate heat exchanger and the solver is coming up with some error messages. The first says that a vortex crosses the pressure opening and the second says that my heat transfer rate goals are invalid. How can I get the heat transfer goals to be valid as I need...

I am designing a flat plate heat exchanger for a project and I am not sure where to start with the hand calculations, specifically the LMTD and E-NTU methods, also how to work out the parameters which i will need to complete these methods such as area and number of plates. My deadline is soon...

Hi, I currently have a project running involving dynamic insulation. I am struggling to develop a 1D transient analytical model to compare to my experimental results. I have used the separation by variables method in the most basic form over 1 solid material but have failed to adapt this to 3...

I'm having a problem with understanding how energy flows from one body to the other. So gases at high pressure travel towards low pressured areas. So there is a reason behind this. Since molecules of gases have the tendency to move away from each other, they travel towards low pressured areas...

Water is being sprayed at a hot flowing material to cool it from 350F to 290F. Let's assume that steam is produced when the water hits the hot material. How would I set up the heat transfer equation to solve for the mass flow rate of water required to cool it from 350 to 290? Assumptions...

I am working on the simulation of a heater in ANSYS. I'll explain the geometry: - Top plate - Ceramic Porcelain material - 2.65in x 4.8in x 0.06in - carries a small heater (2in x 0.125in x 0.01in) on top of it which generates 18W of heat. - Bottom heater - 5.8in x 3.65in x 0.03in - Stainless...

So a friend of mine is living in an apartment with central heating but the radiators are removed, so there are just the pipes. He seems to think that if you cut aluminium jar caps and cover the pipes with them, it will increase the surface area of the pipe and therefore heat the room more. The...

Hi! I am modelling heat transfer through the oxide scales on the surface of steel but I cannot find the accurate properties of oxide scales. I need thermal conductivity, density and specific heat capacity. They shloud be dependent on temperature. I have found only one book in which are some...

Hello, I have a swimming pool with a waterfall feature. I need to know how much does the waterfall contributes to cooling the pool. I tried to use Newton's law of cooling, but I have a problem with the Heat Transfer Coefficient in this case. Following are the Givens: Waterfall Width= 5m...

OK so I have a little issue I'm dealing with.. here are the basics.. There is a material that was filtered and came out of the filtration process at about 330 degrees (it comes out as a solid filter cake). It somehow caught on fire which caused the deluge system to activate. I just want to...

Hi, I need to measure heat transfer coefficient in the block channel. However, the block is not general block. Inside block, there is trapezoid object. So, water flow rate in the first is low speed because big square. Then the square size will decrease then the speed is high. Do you know how...

So the internal energy of a system changes if work or heat is transferred between itself and its environment. Say you compress a gas and therefore do work on it, increasing its internal energy. According to Newton's 3rd law, shouldn't the gas also do work on its surroundings. How come this isn't...

I'm going through the solution to a problem that was assigned to my class and there's a step I don't really understand which I think is a concept I'm misunderstanding. 1. Homework Statement The curved surface of a cylinder of radius R and length L is insulated. The face at x = L is maintained...

Aluminum foil reels have to be preheated for manufacturing but it's inefficient (the doors aren't sealed and the material isn't in close contact with heating elements at the sides). I'm considering an initiative of more efficient design. How difficult would it be to evaluate heat transfer if...

Hey, I have a question regarding heat transfer. I was wondering if a heat sink works in both ways equally effective. What I mean by that is if we submerge the fins of a heat sink into a hot environment, will it transfer the heat equally effective to cold environment which it's mounted on...

In terms of Heat equation it is d2T/dx2 + qgen = qstored assuming steady state, heat flows in one direction. But I have seen examples where energy is balanced in terms of qconv + qcond + qgen= qstored Why is the first equation just not the first derivative of Temperature with respected to x...

I am not familiar with non steady-state heat transfer problems, any resources on where I could get started would be a huge help: There is a pipe filled with a fuel/air mixture. This mixture is ignited at one end of the pipe, so that the flame front propagates through the pipe. How can we...

Homework Statement Steam in a piston-cylinder assembly undergoes a polytropic process. Kinetic and potential energy effects are negligible. For the process, determine the work and heat transfer, each in Btu per lb of steam. p1 = 100 lbf/in2 p2 = 40 lbf/in2 v1 = 4.934 ft3/lb v2 = 11.04 ft3/lb...

According to this article, it is beneficial to scale down heat exchangers due to the decreased distance the heat has to travel, and therefore the decreased thermal resistance and increased heat flow. "the best way to remove heat from a CPU is to minimize the distance heat must travel from a...

This question is easier to explain with an example. A silicon microprocessor consumes 100W of real power. If the surrounding air has a temperature of 22°C, and the temperature of the microprocessor must stay below 60°C, how much heat must the microprocessor dissipate? This isn’t a homework or...

Hi, I am working on constructing a thermal circuit where I am using the concept of natural convection from a vertical hot plate in the shape of a DVD. In order to calculate the Grashoff number, I have to use the characteristic length. What should I take as my characteristic length? The disc OD...

Hello all. I need to design a radiator for 43kw heat dissipation. I have used the LMTD method for finding out the contact surface area of the radiator. But I have a small problem. I cannot find the area unless i know the overall heat transfer coefficient. Can somebody please give an estimate of...

Not sure if I'm getting this right, my answer seems very small, can anyone advise? Question- butanol at a temperature of 28oC is pumped at a velocity of 14ms-1 through a 100mm diameter tube kept at a wall temp of 90oC. The properties of butanol are below. Determine the convective heat...

How do I find the heat transfer coefficient for a meteorite? The meteorite is made of carboneus chondrite, but approximations with heat transfer coefficients for regular stones or rocky materials would be just as fine. Furthermore, how would I calculate the energy required to vaporize 1 g of...

One quick question about heat transfer. during conduction heat transfer occur when molecules collide with each other .heat from one end of the object is transferred to other end .when molecules from end 1 collide with near by molecules of end 2 they transfer their energy to those nearby...

I am a little confused, because I know how refrigerators work with a refrigerant and a compressor and heat exchanges, and I am looking to build one myself, just wondering because I was looking for refrigerator compressors online to buy. Do they have an inlet for refrigerant or is the...