Power required by air compressor with intercooling feature

In summary: RTln(V2/V1)/t. In summary, an air compressor is used to compress air from 100kPa and 30°C to 800kPa at a rate of 120kg/min. The power required for the compression can be calculated using the ideal gas law and the mass flow rate.
  • #1
jasoncurious
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An air compressor is used to compress air from 100kPa and 30°C to 800kPa at a rate of 120kg/min. By having the inter-cooling feature the compression is done at constant temperature of 30°C. calculate the power required for the compression.

Known data:
P(initial)=100kPa
P(final)=800kPa
Temperature(constant)=30°C
Mass flow rate=120kg/min=2kg/s

Since the velocity, elevation and work done is not mentioned, I assume that W(out), KE and PE=0.
Thus the equation:
m(h1+KE1+PE1)+W(in)=m(h2+KE2+PE2)+W(out) is reduced to:
mh1+W(in)=mh2
Then, W(in)=mh2-mh1

I have tried looking for the values for h1 and h2 at the ideal gas table(since the air has high temperature and low pressure with respect to its critical properties), but then I realized that both of them are the same, which led to W(in) been 0 (which is impossible). My friend mentioned the "state postulate", others use the PVln(P1/P2) to determine the work done.
I want to know if my attempt is the right one, if not, then what's the right way of doing this question. Your help will be greatly appreciated. God bless you all.
 
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  • #2
Your attempt is not the right way of doing this question. The correct way to solve this problem is to use the ideal gas law. You can use the following equation: PV = mRT where P is the pressure, V is the volume, m is the mass, R is the gas constant, and T is the temperature. You can then rearrange the equation to solve for the work done (W): W = mRTln(V2/V1) You can then calculate the power required by multiplying the work done by the mass flow rate: Power = mRTln(V2/V1)*m
 

FAQ: Power required by air compressor with intercooling feature

1. How does intercooling affect the power required by an air compressor?

Intercooling is a process in which the compressed air is cooled between stages in a multi-stage compressor. This results in a decrease in the temperature and volume of the air, which reduces the specific work required to compress the air. Therefore, intercooling can significantly decrease the power required by an air compressor.

2. Is intercooling necessary for all air compressors?

No, intercooling is not necessary for all air compressors. It is typically used in multi-stage compressors, where the air is compressed multiple times. In single-stage compressors, the air is compressed only once, and intercooling is not needed.

3. How does the intercooling feature impact the efficiency of an air compressor?

The intercooling feature improves the efficiency of an air compressor by reducing the amount of work required to compress the air. This results in less energy consumption and lower operating costs.

4. Can intercooling be added to an existing air compressor?

Yes, intercooling can be added to an existing air compressor. However, it may require modifications to the compressor and additional components, such as intercooler coils and piping, to be installed.

5. Are there any disadvantages to using an air compressor with an intercooling feature?

One potential disadvantage of using an air compressor with an intercooling feature is the added complexity and cost of the system. Additionally, if the intercooling system is not properly maintained, it can lead to decreased efficiency and increased energy consumption.

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