Heat Definition and 1000 Threads

I am looking at an Energy Balance equation (see images) for latent and sensible heat. However, I don't understand the terms 'advection of latent heat' Alat and 'advection of sensible heat' Ah. They positively enter the system, but how do they differ from latent and sensible heat itself?

Homework Statement The second law of thermodynamics says that we cannot have an engine which converts all the heat into the work.This is because an engine has to work in cyclic process and we cannot have cyclic process which converts all the heat into the work. Right? For example, in Carnot...

Homework Statement Homework Equations I'm not sure. The Attempt at a Solution I tried to solve this as you would with electric charges. I added up the temperatures and then divided by 2, to get (C) 17.5 degrees Celsius. The answer key gives the answer as (D) 20.0 degrees Celsius. I'm not...

// moved from general forum, homework template missing // Assuming that by the word "Work", work on the system is meant. Both heat and work is energy in transit. I think heat is work done by constituent particles of a system on another system in contact. Now the work done by us on a system...

Hello, I got this problem but I don't know How can Find Heat loss (or gain) - Q3 - from the curved surface of the metal rod to the surrounding. This is the problem: A metal rod, of diameter (d) and length (L), runs between two hot walls at temperatures, T1 (Wall 1) and T2 (Wall 2)...

Homework Statement https://i.imgur.com/f2vSXtq.png Homework Equations https://i.imgur.com/Kjy1Tzh.png The Attempt at a Solution In this question, the pressure is different at different point, in other words it is not constant throughout the system. Why the solution use c(p) (or "enthalpy" h...

Hello, I have studied about heat transfer through conduction only in steady state but I wondered about this problem that I created. Suppose you have a box that is insulated from all sides but Suppose a constant heat flow from that wall. Inside that box you have M kg of water at the same...

Homework Statement Modify the initial conditions (for the diffusion equation of a circle) to have the initial conditions ## g(\theta)= \sum_{n=-\infty}^{\infty}d_{n}e^{2\pi in\theta} ## Using the method of Green's functions, and ## S(\theta,t)= \frac{1}{\sqrt{4\pi...

So, if frequency(max) of light emitted from an object proportional to temperature in kelvin, how can sun have max frequency around the yellow region while blue flames are much less hot?

My doubt it is simply if have other reason to don't use this principle for the specific heat of diatomic gases. Homework Equations $$U=NkT=nRT$$ $$u_n=\frac{U}{n}=RT\text{ molar energy}$$ $$u_N=\frac{U}{N}=kT\text{ average energy}$$ $$Z=\sum{e^{-\omega_i/kT}}\text{ with $\omega_i$ particular...

Homework Statement Show that k(x,0)=δ(x). Where k(x,t) is the heat kernel and δ(x) is the Dirac Delta at x=0. Homework Equations k(x,t) = (1/Sqrt[4*π*D*t])*Exp[-x^2/(4*D*t)] The Attempt at a Solution I am just clueless from the beginning. I am guessing this is got to do with convolution...

Hi All I need to do an evaluation of a pilot plant heat exchanger that we have installed and see if it would be better suited than our current bigger installations. I was trying to calculate the effectiveness of the heat exchanger but I keep on getting 1 with the NTU method. Below is the...

Air is flowing through a pipe, through a heater matrix. Flow, Inlet temperature and heater power vary. Is it possible to calculate the heat capacity of the matrix by using the Inlet & outlet temperatures, power & flow? I'm assuming no heat loss to the pipe walls to make it easier, but I'm not...

Homework Statement 'A shell and tube exchanger is used to do heating, with single shell and 2 tube passes. There are 70 tubes each with an outside diameter of 25mm and length of each tube pass is 6m. ' I am wondering whether the 70 tubes are in between the 2 tube passes, or is it 1 tube pass...

Hello, So I am assembling some testing equipment. I have an active circuit, microcontroller, and two battery packs inside a black polypropylene case (which is around 1 ft x 1 ft x 0.5 ft). I was performing a thermal analysis because I want to make sure the electronics do not heat up past around...

##\displaystyle \frac{\partial u(x,t)}{\partial t}-p(x) \frac{\partial^2 u(x)}{\partial x^2}-\frac{\partial p(x)}{\partial x}\frac{\partial u(x)}{\partial x}=f(x,t)##. With periodic boundary conditions: ##u(x,t)=u(x+2\pi,t)##. The right hand side is also a periodic function of space, and it can...

Hi I am trying to do a transient heat transfer calculation. The water flowing through the pipe is laminar (1 m/s, id = 0.0127 m, Re_d = 0.01) transferring heat to the pipe via convection, then the pipe (od = 0.015875 m, l = 144 m) transfers heat to the ground again via conduction. I found this...

Homework Statement I was trying to validate a calculation I didusing ANSYS fluent, it's about a flow of water that enters a tube, the tube is 16m long and is being heated with a Heat Flux of q'=1077328,47 [W/m^2], now after the simulation runs and I check the results I find out that the steam...

Hi everybody, How do you find the heat radiation between two surfaces that aren’t perfectly parallel or perpendicular to each other? I know that the view factors play a part, however, I can only dig up view factors for parallel and perpendicular surfaces...

Does electron really vibrate to produce heat energy or is it atom in whole to produce heat?

halo every one... i have question . if i have pipe inside building with 9 floor's length ,and i have calorie meter between the incoming and outgoing pipe's. how i can calculate the losses of pipe if i now that temperature inside building is 22. i want to be sure that the system working normal. i...

When we heat something then it breaks and it is due to the transfer of energy . But what if we ignore the energy and thought it as Force I.e. the object molecules break due to Force applied on each other ( molecules) . So is it right to say heat apply Force.?

Homework Statement solve the following heat problem using FFCT: A metal bar of length L, is at constant temperature of ## U_0 ## , at ##t=0## the end ##x=L## is suddenly given the constant temperature of ##U_1## and the end x=0 is insulated. Assuming that the surface of the bar is insulated...

Homework Statement Solve the following heat Eq. using FFCT: A metal bar of length L is at constant temperature of Uo, at t=0 the end x=L is suddenly given the constant temperature U1, and the end x=0 is insulated. Assuming that the surface of the bar is insulated, find the temperature at any...

Hi, I am looking to simulate a very - seemingly - simple case. Any advice on a software package would be helpful - preferably gui which doesn't have a steep learning curve. I want to model the heat flux into a sphere from the outside. The dimensions of the sphere are not important to me. I...

n the heat transfer analysis of boundary layer flow of viscoelastic fluids many researchers see the variation of temperature of fluid inside the boundary layer with Prandtl number, for which they use prandtl number 0.7, 2 , 3, 4 .. This is what generally the researchers do.. Currently i am...

When a refrigerant crosses a heat exchanger device or has some heat added into it, like condenser/evaporator or boiler/cooling tower, does the phase always change? If that's so, why? Or do we need to check if the temperature is above or under the boiling point?

I always figured heat is the property of being 'jiggly' at a molecular level, and conduction is when a very 'jiggly' object comes in contact with another object and transfers that 'jigglyness' to the latter. But how does radiating heat work? That doesn't make sense to me. Is heat a wave? That...

Homework Statement The dot in Fig. 19-18b represents the initial state of a gas, and the isotherm through the dot divides the p-V diagram into regions 1 and 2. For the following processes, determine whether the change Eint in the internal energy of the gas is positive, negative, or zero: (a)...

Homework Statement Consider the slab shown in Fig. 18-18. Suppose that L 25.0 cm, A 90.0 cm2, and the material is copper. If TH 125 C, TC 10.0 C, and a steady state is reached, find the conduction rate through the slab. Homework Equations Pcond = Kc *A*(TH - TC)/L K = 401 W/m*k The Attempt at...

Homework Statement A 0.530 kg sample of liquid water and a sample of ice are placed in a thermally insulated container. The container also contains a device that transfers energy as heat from the liquid water to the ice at a constant rate P, until thermal equilibrium is reached. The...

Homework Statement The constant-volume heat capacity of a particular simple system is c_v = AT^3 where A is a constant. In addition the equation of state is known to be of the form (v-v_0)p = B(T) where B(T) is an unspecified function of T. Evaluate the permissible functional form of B(T)...

Recently there was a discussion on a tree planting forum. Contractors in the field will put a tarp over boxes of seedlings to keep them cool. The tarp is white on one side, and aluminum coated mylar on the other. Discussion was: * do these work? * Silver side in or out? Whether white or...

Hello, I have a question for expert in termodynamics. Let's assume I have a copper conductor made of two big disks connected with a very thin wire. Let's imagine I have a current pulse starting somewhere in the wire, and assume the current density is high, like 100A/mm^2. This current will...

Hi, I want to simulate a forced convection cooling problem. Air at ambient temperature is forced through a fan into a system to cool electronics and I would like to assess the temperature of the outlet air. Actually I'm interested in the delta between the ambient and outlet temperature. This...

Homework Statement A cylinder with a heavy ram/piston contains air at T = 300 K. Pi = 2.00 * 105 Pa, Vi = 0.350 m3, Mr = 28.9 g/mol & Cv = 5R/2 (a) What's the Molecular Specific Heat of an Ideal Gas, with a constant volume, computed at J/KgC ? (Cv) (b) What's the mass of the air inside the...

https://www.engr.colostate.edu/~allan/thermo/page8/page8.html The link above takes you to a site I have found to be very helpful in my studies of the Otto cycle, but on this particular page, it depicts an equation for the rate of change of cylinder Pressure vs. crank angle, and in this...

Ques: I would like to calculate the time taken where the internal pipe's temperature would reach 150 degree Celsius too. A heat source will be constantly feeding on outside pipe where the temperature will be maintaining at 150 degree Celsius. Feel free to make any assumptions if there is...

Homework Statement This isn't a homework question but something I'm working on that I thought should be simple. Two disks (area ##A## and thickness ##d##) are joined together and placed under a radiation heater in vacuum, so that one side of the top disk is heated with a constant power. Assume...

Homework Statement [/B] At high temperatures the nitrogen molecule behaves like a one-dimensional harmonic oscillator. In this situation, estimate how much heat must be added to the system in order to increase the temperature of 1 mole of nitrogen gas by 10 degrees Celsius (for constant volume...

I found out that Power of an electrical circuit will be equal to the work done divided by the time T for which the power by the cell or battery is exerting to keep a potential difference V in the circuit for a charge Q. Hence, Power= Voltage*Charge/time Which then can be written as: Power=...

How long does it take for the temperature on Earth to cool down after the sun has set? I want to know if the total solar eclipse will change the temperature.

What is definition of heat? And why it's unit is kgm^2/s^2? I couldn't be able to link the unit to the definition.

Homework Statement Consider a system formed by two phases of a substance that consists of a single class of molecules. Determine the specific heat ##c## of a vapor pressure and temperature ##p## ##T## on the curve of liquid-vapor equilibrium. Consider the steam as an ideal gas. Data: ##c_p##...

Homework Statement A composite pipe made of steel pipe ( ks = 16 W/m.K) of inner and outer radius of 0.5 and 1.0 cm and a plastic pipe (kp = 0.092 W/m.K) of inner and outer radius of 1 and 1.25 cm, respectively. If the inner surface of the steel is maintained at 900 °C and outer surface of...

Azobenzenes trap heat when exposed to sunlight due via the principle of photo-isomerism. But this occurs in nanoseconds. I was wondering if we can store this heat for hours and utilize this later on. Is there any way to do that?

Homework Statement A plastic pipe (k=0.092 W/m.K) of inner and outer radius of 1 and 1.25 cm, respectively. If the inner and outer surfaces are at 60 °C and 30 °C, respectively. The rate of heat transfer per unit length is close to: a) 98 W/m b) 89 W/m c) 78 W/m d) 168 W/m e) 112 W/m...

Homework Statement Determine the heat loss in the circuit that is connected in series with two batteries (12 V and 6V) and two resistors (6ohms and 4 ohms). Homework EquationsThe Attempt at a Solution I used the difference in P = V^2/R, the power dissipated in the circuit, to calculate the...

So recently I've become familiar with concepts like specific heat, and we use a formula Q=mcΔT to calculate the Joules necessary to heat up say a kg of water from 50 to 70 degrees celsius. Now I was wondering if there is a equation that incorporates the amount of heat lost to the atmosphere...

Looking back to heat transfer by convection, which means denser molecules move down, lighter molecules move up. And then water at 4°C expands when cooled further, and at 0°C it contracts when heated. So if water at 0°C in a container is heated from the bottom, its molecules should...