# heat

1. ### Latent Heat

One more question- How much heat is required to change 1.83 kg of solid lead at 135°C to liquid lead at 327°C? I'm assuming I have to use both the equations, Q=cm△T and Q=Lf*m. I wasn't sure how to go about it so I solved Q=Lf*m and got 4.28e4, then used it for Q=4.28e4(192) and got...
2. ### Specific Heat Problem

Hello again, I'm trying to figure out this problem- A 2.4 kg iron ball is dropped from a height of 14 m onto a concrete roadway, and 2.5% of its kinetic energy at the time it reaches the ground is transformed into internal energy in the ball itself. (The rest of the energy is transmitted to...
3. ### Heat Transfer between 2 control Volumes

Hey I'm new to the forums, but I could really use some help with a problem. My school does a senior design project where we design and build some prototype system. My team has a client that wants an internal cooling device through inhalation. I'm the only team member who has had experience with...
4. ### Greetings all

Hi everyone, I am currently seeking help for one of my assignments involving the topic of thermodynamics in domestic heating. I will be comparing the gas furnace and AC heater for benefits, advantages and vice versa. Does anyone have any suggestions on how or what I should do to calculate the...
5. ### Why entropy is more if heat is more?

As we know what heat is. Heat is molecules having more kinetic energy. Kinetic energy increases as an object gets hotter. So hotter object has more energy i.e kinetic energy. So with more energy there are more possible arrangement of the molecules so entropy is more. Does this mean as an...
6. ### Enthalpy and heat advection

Hi all, I'm confused about the role/definition of enthalpy in heat advection. I have an isobaric system with heat conductivity k (W/m*K) through which an ideal gas diffuses with given specific heat capacity C_p(T) (J/mol*K) and mass flux \vec{j_m} (mol/m^2*s). What I would like to formulate is...
7. ### Heat absorption in reversible isothermal expansion

2kgs (total mass) of steam goes through a revesible isothermal expansion at 500 degrees celcius. During the expansion the pressure drops from 300 kpa to 200 kpa What is the heat absorbed by the steam during this process? I guess that steam cannot be assumed to be ideal which makes the...
8. ### Film condensation heat transfer coefficient on helical tube

Hi guys, I am working on my final year project and struggling to calculate the film condensation heat transfer coefficient on the my condenser. All I could find was the heat transfer coefficient on both vertical and horizontal plates and tubes. I can't seem to find h for helical tube that is...
9. ### Condensation heat transfer coefficient on helical condenser

Hi guys, I am working on my final year project and struggling to calculate the film condensation heat transfer coefficient on the my condenser. All I could find was the heat transfer coefficient on both vertical and horizontal plates and tubes. I can't seem to find h for helical tube that is...
10. ### calculate the temperature due to Power loss over a res.

Hi All, Having the following problem I am trying to solve I am an electronics guy some of e physics eludes me in my calc. Here goes.... I am supplying 125Vac into a R which is a 20kohm resistor where I have a 12V zener in series to GND. P_loss = (125Vac - 5V)^2 / R P_loss = 0.72W So lets...
11. ### solving heat PDE using FFCT

the problem is 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, find the temperature at...
12. ### Condensation heat exchange design

Need to design efficient condenser for a close loop system which has high high air mass fraction (about 70-90%) compared to vapor (FLUROINERT FC 72) we all know the condenser becomes very much inefficient in a system, if teh system contains air which is considered non condensible. Is...
13. ### Maximize heat transfer in ductwork

Yes, you read that right. In contrast to the typical goal with ductwork, I'm trying to MAXIMIZE the amount of thermal energy transferred from the air inside the ducts to the surrounding environment. Here's the situation: I have roughly 12 feet of distance to cover with a 4" diameter duct. One...
14. ### Integration of heat transfer rate equation

Hi everyone, I am trying to do an analysis of a steam pipeline to compare the use of steam to warm up a pipeline after shutdown versus other methods (heat strips). The one thing I am trying to figure out is the units for the integration of the heat transfer rate equation which is...
15. ### Does more heat imply more energy?

We know that ultraviolet light has more energy. So can we say that ultraviolet light is hotter than violet spectrum of a hot object?
16. ### fundamentals

What are the basics High school student should know when he is studying Thermodynamics ?
17. ### Heat transfer in molten metals

Hi all, I am currently working on a heat transfer problem for a galvanizing process. I would like to determine the time it takes wire to saturate to the temperature of the molten lead it is pulled through. The problem I have is in calculating the heat transfer coefficient h. The wire is...
18. ### Heat transfer in double pane window

You need to design a double plane window that is comprised of two 5mm thick slabs of window glass (mean thermal conductivity 0.84 W/(mk)) with a gap of stagnant air (mean thermal conductivity 0.02W/(mk)) in between them. The room temperature is 298k, outside temperature is -15c. The heat...
19. ### Heat flux: porous media/air interaction

Dear community, I have a question concerning the thermodynamic behaviour of a theoretical column experiment: Assume I have a "1D"-column of 50 m sand. At the top the surface air temperature is -25°C. At the beginning of the experiment the sediment column is almost completely filled with tap...
20. ### heat transfer in atmosphere

A cirrus uncinus cloud (a hook-like cloud appearing at an altitude between 5 to 15 km and indicating a slowly approaching storm) has an average thickness l=1000m The extinction coefficient for the cloud is sigma 2.2*10^-3 The intensity of the irradiation at the top of the cloud is 830w/m^2...