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9 votes

Energy required to raise temperature of water flowing through a heater

You just need to convert the volumetric flow rate to a mass flow rate by multiplying by its density. This is easy for water: $$10\ \mathrm{l/hr} \cdot 1\ \mathrm{kg/l} = 10\ \mathrm{kg/hr} = 10^4\ \...
Dave Tweed's user avatar
  • 6,884
7 votes
Accepted

Radiators in series or parallel?

The efficiency of any radiator (heat exchanger) is a function of the temperature difference between the two fluids in question. All else being equal, a heat exchanger with a greater temperature ...
Dave Tweed's user avatar
  • 6,884
7 votes
Accepted

In a diesel engine, does more heat leave the engine through the tailpipe or the radiator?

They are very nearly equal for typical four-stroke non-turbo diesels under load. A turbo diesel under load should have slightly more radiator loss than exhaust loss. At the bottom is a link to the ...
Phil Sweet's user avatar
  • 4,755
5 votes

Energy required to raise temperature of water flowing through a heater

$$P = \dot m \cdot C_p \cdot \Delta T $$ Where $P$ is the power required in Watts ($Joules/sec$) $\dot m$ is the mass flow rate ($kg/sec$) (you'll have to convert the volumetric flow given to a mass ...
DLS3141's user avatar
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5 votes
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Furnace Combustion Air Properties

the outside air is colder, but the flame temperature is still much much hotter than that so the difference cold inlet air makes on the outlet temperature of the furnace will be small. The same ...
niels nielsen's user avatar
4 votes

Heat Exchanger Design - finding necessary variables

I found the average of the inlet and outlet pressure and temperature in the hydrocarbon stream and then used those values in the ideal gas equation to find the densities of each hydrocarbon Why would ...
Algo's user avatar
  • 2,150
4 votes

estimating the surface area of a steam coil immersed in a tank

One thing to consider is that pipes used for heating like this are normally « finned » to increase the surface area - fins can be small discs fitted to the pipe or even wire loops - both increase the ...
Solar Mike's user avatar
  • 15.8k
4 votes

Energy required to raise temperature of water flowing through a heater

10 litres per hour 10 kg per hour 10,000 g per hour 166.66 g per minute 2.77 g per second Every second, you need to raise the temperature of 2.77 g of water by 30 °C. 2.77 g of water 4.18 J/g ...
Ian Boyd's user avatar
  • 141
3 votes

why not put the compressor right next to the evaporator?

The evaporator is usually in the area to be cooled ie where the people work, read etc As the compressor takes space and tends to be noisy it is located away from that area. That makes the system in ...
Solar Mike's user avatar
  • 15.8k
3 votes

Valve first,then heat exchanger OR heat exchanger first then valve

I think the key information is that the liquid is saturated. This means any reduction in pressure will lead to partial vaporization and two phase flow. For heat tranfer best overall heat transfer ...
Ohio ChemE's user avatar
3 votes

What is the fouling effect (in rate, foulant thickness) of sand inside tube side of a shell and tube heat exchanger?

There is quite a bit to unpack here, so I may need to deconstruct your question a bit. Your question is surrounding the fouling rate of a Shell & Tube (S&T) heat exchanger which I will get to, ...
ChemE mang's user avatar
3 votes

In a shell and tube heat exchanger, does reducing flowrate affect the outlet temperatures?

I assume you are referring to a exchanger like the following: If : the external dimensions of the heat exchanger remain the same. the tubing diameter remains the same. the number of tubes changes (...
NMech's user avatar
  • 24.3k
3 votes

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

In the steady-state case you describe, the thermal conductivity determines how much heat (kW) a material will trasnmit per unit surface for a given temperature difference (K). In heat exchanger ...
mart's user avatar
  • 4,781
3 votes

Cooling system to maintain 0.5 °C at 95% humidity

At near-freezing temperatures, the amount of water vapor in the air to get 95% relative humidity is tiny, this is no problem. I recommend filling 55 gallon poly drums on pallets with water, park them ...
niels nielsen's user avatar
3 votes
Accepted

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

Several high performance houses with lots of insulation have been designed with wood stoves that are surrounded by lots of stone to give the thermal mass. Some are still giving out heat 24 hours after ...
Solar Mike's user avatar
  • 15.8k
2 votes

Heat Exchanger Design - finding necessary variables

Between 135 F and 100 F I don't think the heat capacity or density would vary much so using average properties should be fine. If you want to be more conservative you can use the higher Cp between ...
Adri Jamil's user avatar
2 votes

Fluid allocation for shell and tube heat exchanger

This is a good start for your decision and you can probably get away with it however you should factor in everything that influences that decision. Cleaning Corrosion Fouling Temperature Viscosity ...
idkfa's user avatar
  • 1,734
2 votes

Radiators in series or parallel?

Assumptions: "Radiator" means a forced-air air-to-fluid heat exchanger. Radiators in either setup will pull from their own fresh air source (not from the exhaust of another radiator). Ignoring ...
ericnutsch's user avatar
  • 8,151
2 votes

How to control precisely the wall temperature of a tubular reactor?

I've had this problem before, albeit not with such a tight temperature range. I would recommend immersing the reactor in a fluid with high thermal mass, then I would circulate and temperature control ...
Drew's user avatar
  • 1,971
2 votes

Modelling reactor jacket with or without insulation, how to proceed?

Full Analysis Perfectly Insulated System The best case is to analyze this system in both the time and position domains. The time domain considers the variation of the reactor temperature $T_r(t)$ ...
Jeffrey J Weimer's user avatar
2 votes

Process fluid flow in a fired heater

It is just getting as much heat as possible. Heat flows from hot to cold. The convection section is a much lower temperature. The convection section is basically waste heat in flue gas. The cold ...
paparazzo's user avatar
  • 489
2 votes

why not put the compressor right next to the evaporator?

What you describe is quite common where there isn't any problem with power and noise. It requires a bit more sophistication to manage the superheat. And yes, you need to quiet the thing some. I ...
Phil Sweet's user avatar
  • 4,755
2 votes

How to periodically shut down a recirculating hot water solar thermal system

I would not mess around like this at all. I would make a secondary heat dump (old radiator in the garden, swimming pool...) and divert excess heat there.
Solar Mike's user avatar
  • 15.8k
2 votes
Accepted

Why do plate exchangers typically serve lower pressure fluids than shell and tube heat exchanger?

Because the plates are usually very thin for their dimensions and tubes tend to have more strength for the pressure loading. I would check better references such as Simonson: Heat transfer for more ...
Solar Mike's user avatar
  • 15.8k
2 votes

Why Nusselt number for laminar flow in a pipe is independent of Reynolds number

The Nusselt number is about the ratio of conductive and convective heat transfer across a boundary. The Reynolds number is about how a fluid is moving - usually laminar (below 1700), turbulent (above ...
Solar Mike's user avatar
  • 15.8k
2 votes
Accepted

Why Nusselt number for laminar flow in a pipe is independent of Reynolds number

In general, heat transfer with internal flows - like flows in a pipe - does depend on Reynolds Number. For small enough Reynolds number, the flow is laminar and the nature of the laminar flow is such ...
ttonon's user avatar
  • 417
2 votes

When is a heat exchanger worth it?

If this is a student design problem to see whether you understand the principles, make it as easy as you can, use steam and cooling water. Calculating all the pressure drops on the weird pipe systems ...
Gwyn's user avatar
  • 229
2 votes
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How to transfer air heat easily?

you should look into district heating solutions. For your application the lengths are quite small so you probably can get away with using an air duct and a fan to push the air through. However, a ...
NMech's user avatar
  • 24.3k
2 votes

How are heat exchangers normally calculated?

Most of the calculations that I find in books are about calculating the heat transfer rate, which I'm not sure why I would care about. Let's see if that's true. What I imagine is the case in a real ...
Transistor's user avatar
  • 10.8k
2 votes
Accepted

How are heat exchangers normally calculated?

Your specification is that you know the two inlet temperatures, $T_{h,i}$ (hot in) and $T_{c,i}$ (cold in). Interestingly, you also say that you want to cool the hot stream to a defined temperature $...
Jeffrey J Weimer's user avatar

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