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:
$$10\ \mathrm{l/hr} \cdot 1\ \mathrm{kg/l} = 10\ \mathrm{kg/hr} = 10^4\ \...
- 6,884
7
votes
Accepted
Radiators in series or parallel?
The efficiency of any radiator (heat exchanger) is a function of the temperature difference between the two fluids in question. All else being equal, a heat exchanger with a greater temperature ...
- 6,884
7
votes
Accepted
In a diesel engine, does more heat leave the engine through the tailpipe or the radiator?
They are very nearly equal for typical four-stroke non-turbo diesels under load. A turbo diesel under load should have slightly more radiator loss than exhaust loss.
At the bottom is a link to the ...
- 4,755
5
votes
Accepted
Furnace Combustion Air Properties
the outside air is colder, but the flame temperature is still much much hotter than that so the difference cold inlet air makes on the outlet temperature of the furnace will be small.
The same ...
- 14.7k
4
votes
Energy required to raise temperature of water flowing through a heater
10 litres per hour
10 kg per hour
10,000 g per hour
166.66 g per minute
2.77 g per second
Every second, you need to raise the temperature of 2.77 g of water by 30 °C.
2.77 g of water
4.18 J/g ...
- 141
4
votes
Energy required to raise temperature of water flowing through a heater
$$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 ...
- 2,145
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 ...
- 2,160
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 ...
- 15.8k
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 ...
- 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 ...
- 121
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, ...
- 605
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 (...
- 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 ...
- 4,771
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 ...
- 14.7k
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 ...
- 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 ...
- 86
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
...
- 1,744
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 ...
- 8,146
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 ...
- 1,931
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 $T_r(t)$ ...
- 2,943
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 ...
- 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 ...
- 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.
- 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 ...
- 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 ...
- 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 ...
- 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 ...
- 229
2
votes
Accepted
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 ...
- 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 ...
- 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 $...
- 2,943
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