Compressor: Discussion and problem solving.

Starting from basic: A compressor is a device used to compress anything feasible. In our case those feasible things are gases or air.
A compressor is an important building block in any power generating cycle which basically consists of four building blocks
  • Evaporator
  • Compressor
  • Condenser
  • Turbine
So a compressor is a work consuming device. And it is only natural that any design engineer would like to have a device working on minimum possible power. So under ideal conditions, a compressor is always expected to work on an isothermal process. While in reality it is never possible. In worst designer would make it work on isentropic process (imagine a PV diagram). Under practical conditions, the process is a Polytropic process. You can very well calculate the amount of work done required in each case by observing the diagram.
[​IMG]So a compressor (I will restrict my discussion to reciprocating one) is generally comprised of stages. A single stage compressor does have some problem associated with it. A single cylinder will be subjected to very high pressure, this is associated with a danger of leakage past piston and the cooling is also rendered ineffective. The cylinder will have to be robust enough for sustaining such extreme conditions.
On the other hand, a multi stage compressor will have effective cooling in between the suction and delivery pressure and suction pressure. However it should be noticed that efficiency increase obtained by adding each stage decreases with each addition of stage. A compromise must hence be made between efficiency and cost incurred for adding each stage. To give you an example, for adding one stage, you require $100 which will promise you 5% efficiency rise, however the next stage though require $100, will only promise you 2.5% efficiency. So the investment should be worth it. A wise man will always be ready to make a compromise.
Another important component here is intercooler, nothing but a heat exchanger is provided, which cools the compressed air/ gas. It is generally provided between two stages.


  • haniyah

    Can you tell me the process of designing finned tube condenser???

    I want to design a condenser for R-22 and R-134a
    Yes, I think you should start a new thread. Post complete information so that we can help you.
  • haniyah
    let say i have 2 TR compressor and this compressor is compressing R-22. The ambient temperature in peak summer reaches upto 52 degree centigrade here in Sharjah. After condensing from the condenser the gas will go through the expansion valve and then into the shell and tube evaporator where it expands and boils by taking the heat of water entering into the evaporator at 30 degree centigrade and leaving at 27.8 degree centigrade and the flow of water is 0.8 kg/s.

    Now i want to design a finned tube condenser.

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