# Questions tagged [heat]

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### Understanding sensible enthalpy for steady-flow system

I am reading a book (Thermodynamics an Engineering approach), I am reading over the section of steady-flow systems with chemical reactions. The book just introduced the following formula for the ...
• 275
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### Does an array of Peltier module need a diode between each module?

I have a bunch of Peltier module that I wish to connect in series/parallel and use them as a thermopile generator. However I was wondering if its necessary to attach a diode between each module to ...
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### Between black and white plastic bag, which one is better to conserve hot and cold respectively?

I want to sell online fresh food and drink, something like in the picture. The food is newly cooked, so it is hot. While the drink is iced, so it is cold. The food mostly will be eaten during lunch ...
67 views

### Water Cooling - Straight pipe vs. Coil Heat Exchanger

I have been looking at a heat exchanger design on the SolidWorks Flow Simulation toolbox. My goal is to cool down water from ambient temperature. To do so, the water flows through a cold aluminium ...
46 views

### How do I calculate the amount of watts that a heating element needs inside a box?

I have an aluminium box (6 mm thick) of about 13.6 m³. Inside the box is a ventilator that can move 140 m³/h and I want to keep the temperature inside this box at about 30 °C. The box is to be placed ...
1 vote
55 views

### Heat calculation with non-constant specific heats

It is always seen that the total heat energy of a material under a change in temperature is given by: $Q = mc_p\Delta T$ But what if $c_p$ changes with temperature? I am asking this because I am ...
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### Why is the compression considered as isentropic in Otto cycle?

We know the ideal Otto cycle is modeled by the two ideal processes isentropic (compression and expansion) and isochoric (heat addition and heat rejection). But why the compression and expansion ...
50 views

### What effect does airflow rate have on heat dissipation if the initial heat varies proportionally to the airflow rate?

If I have a server rack consuming 10 kW of power in an empty room with A/C, what effect does the rate of airflow from the rack's exhaust have on the temperature in the room and the load on the HVAC? I ...
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### Conditions of Separating a Value in Spatial Dimensions

In most of my engineering experience whenever we work in multiple dimensions we can almost always use superposition to get a specific property or quantity in x,y, and z. In these cases, we have always ...
• 57
17 views

### Configurating heat transfer between parts

I am new to Ansys, so sorry if I have some misunderstood parts. I am doing a Steady-state Thermal simulation of a PCB with some of its components. I am currently simulating only the highlighted ...
91 views

### Nusselt number equations for external flow over a single finned tube heat exchanger

I am designing a heat exchanger that will utilize a singular finned tube of around 2" diameter with 4 fins per inch that are 3/4" tall and .03" thick. I am looking at finding the ...
45 views

### How to simulate thermal processes in heat pipes with Ansys

I want to simulate two heat pipelines - first pipe is supply pipe with temperature of 130°C and the other one with temperature of 70°C steady state thermal. Both carry water but under different ...
27 views

### Efficiency difference of an evaporative air cooler based on its dimensions (wider or taller) given that all the other aspects are same

I own an evaporative air cooler of width 28 inches and height 34 inches, I was wondering if a taller air cooler with lesser width (but same surface area as the one I own) would have been more ...
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### Heat exchanger analysis

Hi i have an task of calculating the rates of heat transfer for hot and cold water and discuss the discrepancy's. There are three tests with each one increasing flow rate of the water the same for hot ...
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119 views

### How does this Dyson Airwrap work?

so I’ve been looking into Dyson a lot, and how their stuff works (like AirWrap) and I came across like this picture: Is that bit I circled a heating part please? How can it heat, it just looks like a ...
• 1
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### How to make my kiln airtight?

I need to maintain temperatures of 900 C in a kiln. Making the kiln airtight is very important. After considerable research, I have zeroed in on sheet metal box and mylar space blankets. Am wary of ...
1 vote
941 views

### Can I weld a copper pipe into a CPU heat sink for better cooling?

I have an old laptop which I revived with the addition of a SSD. The problem now with this laptop is that it gets very hot causing thermal shutdowns in the middle of work. I thought of a lot of ...
78 views

### Temporary spray adhesive to hold two plates together for drilling?

If two 24in x 6in x 1in thick plates of 6061-T6 aluminum are temporarily bonded together with 3M Super Trim Adhesive (MSDS), would this be a nightmare to separate? The plate is rated for a max ...
• 355
62 views

### Does it make sense to increase the thermal "dead weight" of a wood stove?

It is general practice to put a bucket of water on top of a wood stove to keep air humidity under control during the burning of the stove. But, such a bucket is also bound to keep some more thermal ...
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1 vote
87 views

### Is a block designed for water cooling effective at dry transmission of heat?

I’m working on a project involving a thermoelectric cooler, and options for small aluminum or copper blocks have been few and far between. However, I found many cheap aluminum and copper blocks on ...
1 vote
886 views

### 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 ...
• 11
142 views

### Calculating Indoor temperature of a structure

Background I am designing a simulator for building designs, and need to track the interior temperature of the constructed building. For simplicity, this building will be one room; meaning the only ...
1 vote
88 views

### Damage to drill through torque?

I've got a Bosch PSB 50 drill, which I'm using to drill through some apparently really tough wood. I don't know why, The drill seems to be struggling, and at times comes to a complete stop. I'm not ...
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23 views

### How to model the kinetics of a reaction while its not being stirred in a batch reactor?

lets consider the following reaction: $$A + B \rightarrow C$$ Where the rate of reaction ($r$) can be expressed as: $$r = k*c_a*c_b$$ Where $c_i$ is the concentration of species $i$ and $k$ is the ...
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70 views

### What can you coat/seal Gallium with?

If I were to make a sculpture out of Gallium, Ga melts at about 85 °F I think, would I be able to spray it with some sort of solvent based or not solvent based coating to help prevent it from breaking ...
53 views

### Minimizing home heating costs [closed]

I live in an old rental house with 12 foot ceilings and zero ceiling fans. I am trying to conserve as much energy as possible as heating costs are expensive. I have placed plastic on all of my windows ...
1 vote
108 views

### Why is the carrier block in a winchester rifle made of brass?

In a Winchester 1873, the carrier block is the part that moves a cartridge from the magazine up to the chamber, and that pushes the previously spent shell up out of the top of the rifle. It moves back ...
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55 views

### Air-to-Water Heat Exchanger - Car radiator

I'm looking for a way to keep a liquid under 50°C. This liquid has a thermal conductivity of .1396 and a specific heat of 2.054 both at 40°C. and a constant energy source submerged in it ranging from ...
1 vote
268 views

### Why does thermal conductivity of a pipe matter in a double pipe heat exchanger?

My understanding is that thermal conductivity is responsible for the time until something will heat up. For example, if you hold a copper bar over a candle it will quickly become hot at the other end. ...
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1 vote
117 views

### In case of solvation , Who converts gaseous ions to aqueous ? Why do we even have gaseous but not solid ions?

We take Nacl and dissolve it in water. There is formation of $Na^+$ and $Cl^-$ gaseous ions along with 2H+ and $Cl^{2-}$ aqueous ions. Then , Na+ is attracted towards $Cl^{2-}$ and 2H+ is attracted ...
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### Mathematical derivation for 1st law of thermodynamics

Mathematical derivation for 1st law of thermodynamics : What I know : 1st law of thermodynamics is known as or derived as the conservation of energy . But how are the terms U , q and W derived from ...
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1 vote
107 views

### What does it mean by average kinetic energy of molecules as temperature?

We say kinetic of molecules as a function of temperature from the equipartition theorem. This means that more is the velocity or mass of the body , more the is the temperature. My Q is why does ...
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1 vote
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### Difference between temperature and heat

It is becoming very difficult for me to understand the difference between temperature and heat. About heat all I have read : Heat exchange is related to as exchange of matter + energy. Heat is ...
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1 vote
171 views

### What is heat , chemical energy and thermodynamics laws restrictions

Below is a text over which I have my questions which I have written below this text: Chemical energy stored by molecules can be released as heat during chemical reactions when a fuel like methane, ...
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6k views

### Why does temperature not increase by putting more logs into the fire

Why does temperature not increase by putting more logs into the fire ? It is a very common observation which I have seen but after some research online I found that it is not completely true. One ...
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1 vote