Thanks for your response, rotw. Apologies for being so vague in my question.
The application is for a small-scale distributed gas (co2) power plant, and yes the RPM is about 50k.
The pressure ratio across the compressor is about 1.1. By useful, I mean the pressure ratio across the compressor...
I'm new to rotary type compressors. I have a radial compressor prototype with the impeller diameter of about 5 cm (yes, it is a small machine). Based on the known inlet conditions and compressor performance characteristics, the calculated pressure and temperature rise across the compressor is...
I already have the compressor efficiency information through the characteristic curves. I'm determining the discharge states using this efficiency data. So, I don't think I have to calculate the efficiency again. Please let me know if I misunderstood.
Thanks for your quick response again.
For now, I'm only interested in the head vs flow curve and the compressor discharge states - mainly to analyze the deltaP rise through the compressor as the inlet conditions or RPM or flow rates change. The polytropic efficiency may be required later, so I...
Thanks for your response, rotw.
Seems like my approach is right! Thanks for confirming it. And I do have the equation of state for the fluid. Given the inlet conditions and the calculated exit enthalpy, can the pressure head be used to determine the discharge pressure? Since I need two...
I have the characteristic curves such as head coefficient vs flow coefficient and flow coefficient vs compressor efficiency. I would like to develop a head (or deltaP) vs flow rate curve mathematically, ultimately determine the discharge pressure. The compressor is not an off-the-shelf item, so...
Thanks for your reply. There is air flow, but I'm thinking it is not running at the rated capacity. Measured air flow across the evaporator is about 0.048 kg/s in contrast to evaporator's rated flow rate of 0.09 kg/s. Flow rate was calculated using measured flow velocity in a rectangular box...
We have a residential R134a air-conditioning system coupled with a R134a based heat engine. The engine and the compressor are mechanically coupled. Based on our tests, the cooling output produced is about 0.07 kW (air side) and the system efficiency is about 2% (at 35 C outdoor temperature). We...
We ran the system with the new motor (higher capacity) and same vane pump, system was working fine without any issues. So, we are ruling out any pump issues.
I calculated NPSHa to be about 18 ft compared to NPSHr from Perry's about 8ft. I used the corrections from Propane as well. This suggests that we are safe in terms of NPSH. What do you think?
We are contacting the pump manufacturer for clarification too.
Good point. We have a flowmeter with sight glass before the pump and that indicates liquid. Also, analyzing test data on the T-s diagram of R134a is suggesting that its completely saturated liquid at the pump suction. We are running the system again with a different pump (but 3/4 hp motor) that...
Thanks for your response. I was afraid of the backpressure too due to increased mass flow. Yes, primary motive is to have higher deltaP and thereby higher shaft work output from the cycle. I have attached a process flow diagram for our system. We ran the system once after changing the motor, but...
We have a small-scale ORC system (less than 3 kWe)that is powering the AC loop where the working fluid in both loops are R134a. The ORC is powered by electrical water heater. Upon testing the system, our hypothesis for very low thermal output (or system efficiency about 2%) is low mass flow rate...
