Questions tagged [thermodynamics]

Questions relating to the various laws of thermodynamics, transformation or movement of a form of energy to another form, primarily but not limited to heating or cooling of a fluid.

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Calculating enthalpy of incompressible liquid and ideal gas?

I have been tasked with creating a Mollier diagram for water using the Redlich-Kwong EoS. In order to calculate the real enthalpy and entropy values using departure functions and residual properties I ...
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In the Rankine Cycle, how does the condenser work without changing the temperature or pressure of the fluid?

The condenser changes the state of the fluid from a saturated mixture to a saturated liquid by rejecting heat, yet the process occurs isothermally and isobarically. How then does it manage to perform ...
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What should be the R value of insulation for charcoal kiln?

I am operating a charcoal kiln. The temperature of the kiln can reach around 800°C. What should be the R value of the required insulation? The outside temperature is around 30°C.
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What are some methods of converting electricity without the use of induction or heat?

I was trying to study exactly how current in a wire is used to do so much in our life and how the energy is converted. But the only methods I have found are by using the resistance of the conductor to ...
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What happens to insulation?

What exactly happens when an insulating material comes in contact with heat through any mode (conduction, convection, or radiation). Something like aluminized mylar will reflect the heat back. How ...
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Flue gas scrubbing in water

What happens if we dip flue gas in water? Flue gas will primarily contain nitrogen and carbon dioxide. Will they escape water without condensing. The water may be slightly higher than room temperature....
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Galvanized Steel Heat Exchangers [closed]

What are the advantages and disadvantages of galvanized steel heat exchanger? I am generating flue gases through pyrolysis process. Can I pass the flue gases through galvanized steel heat exchanger to ...
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Temperature exchange of contact between two metal blocks

I got some feedback from the physics site that these types of thermodynamic questions might be better suited for an engineer. I don't know much about thernodynamics, I'm not taking a course on the ...
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Changing temperature under adibiatic conditions?

Can a temperature change be adiabatic? For example if no 'heat' leaves or enters the system and we compress a fluid such that it's temperature changes is this still adiabatic? If energy is transferred ...
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How much would Jupiter heat up if you accelerate Jupiter out of orbit around the sun using fusion candles? [closed]

So, I responded to a post of someone saying that you could turn Jupiter into a spaceship using fusion candles. I mentioned that doing so would dramatically heat up the planet, especially if you were ...
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how much energy is stored in a car under sun ? (car interior)

When a car is under the sun, the interior is hot. This is due to the interior, especially seats, which are black (or a dark color) so that they heat under sun light and restitute this heat to the air. ...
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Single Stage Equilibrium Problem

I am working on this problem below. Two lb-mol of an equimolar mixture of ethanol-water that is a vapor at dew point at 14.7 psia is mixed with 4.09 L water ($\rho$ = 1 g/ml) at $60^o F$ in an ...
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How do I find the amount of energy needed to evaporate water below its boiling point?

Let's say I have a container filled with water and its surface is in direct contact with air. How much heat/energy do I have to supply to the water such that it evaporates under its boiling point? is ...
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Heat dissipation through multiple layers of different materials

Given 3 materials A, B and C, where A adjoins B, and B adjoins C. A is exothermic. B is a thermal insulator. C is a thermal conductor. Does the thermal conductivity properties of C affect how heat is ...
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How do I compute the saturation temperature of liquid water?

I'm trying to create a code to calculate the saturation temperature of liquid water, when I'm only given the pressure. There are calculators online, but there's no further details about what formula ...
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How do I get the size requirement for my condenser?

I'm planning to build a desalination machine and I want to know at what size the condenser should be. What I did first was that I did a first law analysis of a heat exchanger, with incoming seawater ...
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For a given a molten metal (say copper), how do you determine the best material for a 3D printer flatbed? What about circuit board?

Suppose we had a 3D printer that can spew molten metal out of a 0.1mm hot nozzle and that we can control the heat at the last 5mm of the Tungsten hot nozzle's tip. I'm wondering then how would you get ...
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Will water boil from top-down radiant heating?

I've had a question about the nature of "boiling" for a while. When we observe water boiling, we are actually see several things happen. First, water vaporizes at spot on the bottom of our ...
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Does forced convection account for energy transfer in this case?

I have to confess that thermodynamics is not a friend of mine. My system consists of a volatile droplet sitting on a thermally conductive substrate. The energy balance comprises heat lost due to ...
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Properties of air and gas mixture

While studying a heat exchanger, I have encountered a hydrogen rich fluid stream (enters at 90° Celsius and exits at 120° Celsius) which has composition given in the following form: Air Humidity/Fluid ...
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Simple simulation model of water boiling in a pot?

I want to investigate boiling processes (in the kitchen) by simulation. To this end I assume there is a pot ($m_\mathrm{pot}, C_\mathrm{pot}, T_\mathrm{pot}$) with some water inside ($m_\mathrm{water},...
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Help Understanding this Animation about the Heat Equation?

https://en.m.wikipedia.org/wiki/Heat_equation#/media/File%3A2D_Nonhomogeneous_heat_equation_.gif In the beginning, is the plate being heated from the center? Or is the plate being heated from the ...
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Intra-facility Heat Pump? (HVAC)

Does anyone know if there exists a type of heat pump for moving heat from one indoor area to another? In this scenario there is a room where excess heat is being generated and could be used in heating ...
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Temperature of two aluminium plates heated by a heat source

This is my first question here, so, please, let me know if this is not the right place. I have a 3 m long, 4 mm diameter, 45 W heating cable that I need to place inside a fridge. Unfortunately, it ...
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How much a 0.1 mm air gap between 2 materials will affect heat transfer rate?

I have a disc with drilled holes with a 0.1 mm tolerance. The plate is 6061 T6 Aluminum and I want to insert a polyethylene tube with water in it that is frozen. Assuming some tubes are in full ...
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How does the equilibrium temperature of heat source depend on flow rate?

The scenario I'm considering is a heat source in a closed system which is initially at some temperature $T_{initial}$ and is in equilibrium with its surroundings, being cooled by air (at room ...
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Minimum cooling flow without an outlet temperature

I want to calculate the minimum cooling flow rate $\dot{m}$ for a stirred batch process. The stirrer heats up the reactor's content quite intensively, so first I calculate the temperature of after ...
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I have a short question regarding units of this question

A piston-cylinder machine contains 1 kg of air, initially at v = 0.8 m3/kg and 290 K. The gas is compressed in a slow frictionless process to a specific volume of v = 0.2 m3/kg and a temperature of ...
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seemingly Impossible diesel cycle question

An engine operates an ideal Diesel cycle using argon as the working fluid (R = 0.2081 kJ/kg.K, Cp = 0.5203 kJ/kg.K). At Vmax and Pmin T = 290 K. At Vmax and Vmin of the engine cylinder is 1,200 cm3 ...
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Building a mini scale Air Conditioner

So I am building a I think one can call it air conditioner System for my Ants. But it won't really start to work. In my first run, I tried to transport the cold air into the living area of my ants, ...
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I am struggling to get the right answer regarding the quantification of entropy

1 kg of air in a piston-cylinder apparatus can exchange heat only with a reservoir maintained at 300 K. When 10 kJ of work is done on the air, its state is asserted to change from 1 bar 300 K to 2.5 ...
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Calculating entropy change with Tds relations

The problem I am trying to solve is: A copper block weighing 20 kg is dropped into a large pool of water. The water temperature is 22°C and the temperature of the copper block when it is dropped into ...
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What is the input pressure and a suitable feed composition for a Peng-Robinson EOS Python program?

It's a strange question, I know. Essentially I am supposed to use a Python program to generate VLE data for a binary mixture. I have the components and their critical values (Tc, Pc, acentric factor), ...
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Is it feasible to compress cleaned Biogas?

Biogas generated from anaerobic digestion mainly contains around 50-60% $CH_4$, 35-40% $CO_2$, small amount of $N_2$, saturated $H_2O$ and trace of $H_2S$. It's upgraded to automotive fuel grade by ...
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How to calculate the actual COP of a compression for a given outdoor temperature?

Given a chiller having a nominal COP value, how can we compute the actual COP for a given outdoor temperature. In this regard, is there any difference between compression chillers and absorption ...
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Everyday examples of hydraulic pressure drop generating heat

I'm interested in hands-on examples of voltage drop in electronics dissipating the energy as heat, and, thought that the hydraulics analogy, that is the same thing, might be a good way to intuitively ...
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Does the quality of steam affect the efficiency of a turbine to be calculated?

We were presented in one of our lectures this problem. A steam turbine operates adiabatically at a power level of 3500 kW. Steam enters the turbine at 2400 kPa and 500°C and exhausts from the turbine ...
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Difficulty in understanding electric heater Q relating to its power

Q : An electric heater of power $1000 \mathrm{~W}$ raises the temperature of $5 \mathrm{~kg}$ of a liquid from $25^{\circ} \mathrm{C}$ to $31^{\circ} \mathrm{C}$ in 2 minutes. Calculate : (i) the heat ...
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What is the Specific Heat of Molten Bronze?

I have sources giving the specific heat capacity of bronze as 382 to 385 J⋅kg⁻¹⋅K⁻¹, or as 435 J⋅kg⁻¹⋅K⁻¹. I'm assuming the variation is due to different alloys being considered, which are not ...
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Confused about how combustor pressure is lower than compressor exit pressure in turbomachinery?

I understand the compressor exit pressure is the highest pressure in all of the turbomachinery, and the combustor is a constant pressure process, and since the combustor P is lower than compressor ...
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Isn't the Bernoulli equation just a special case of the Steady-flow equation?

This question is about the following two energy balance equations (assuming no energy input/output): Bernoulli: $\frac{p}{\rho} +\frac {v^2}{2} + zg = const.$ Steady-flow: $u +\frac {p}{\rho} +\frac{...
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Does a higher temperature difference result in a faster rate of heat transfer?

Suppose that I have a thermally insulated tank with hot air at a temperature of 400 C, and the tank is stored in a room with an ambient temperature of 25 C. I also have another identical insulated ...
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Reusing Old Wells to Desalinate Water with Geothermal

Could we reuse expired wells in places like Huntington beach California, to desalinate water? I found the following chart online which suggests that some deeper wells could have temperatures high ...
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Best metal for solar energy collection in an evacuated tube solar water heater

I am building an evacuated tube array for a solar water heater and I am selecting the materials to use for the tubing and the collectors (the places connected to the tubing that help absorb the solar ...
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Why does the torque of an internal combustion engine increase with its rpm at low rpm range?

Here is a simple schematic of the engine. The increase in angular momentum of the crankshaft in one complete cycle would be $\Delta L_{cycle}=\int_{\delta =0}^{\delta =4 \pi} F cos \theta Rdt$. where ...
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Is there a way to make an air conditioner without venting heat outdoors?

Is there a way to make an air conditioner for when you can’t vent the heat outdoors? Can you trap the heat in an object or convert it to another form of energy? For example, could you transfer the ...
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Pv Diagram of a pressure cooker

For a bit of self training in thermodynamics, I've been trying to think of some random systems and go ahead and try to solve them, some of these things I've stolen from random googling of university ...
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Temperature of water decreasing during boil

I am trying to understand this phenomenon that I have noticed with my system (40L capacity boiler with a NTC thermistor located at the bottom). When boiling 10 Litres, the temperature reading reaches ...
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Converting kJ provided to a closed system into final temperature of the system

I'm working a closed system in which starts with 500 grams of steam and 500 grams of water at a temperature of 100 Celsius; 2199.26 kJ is put into the system. I'm trying to find the final temperature ...
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How to convert car power into energy (MJ) used per km?

I am currently attempting to do an energy audit regarding how much energy my car uses per kilometer. I am not sure whether my approach to this is right, and it feels like I have made too many ...
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