R134a Laboratory unit: Question

[James W]

Hi to all!! I'm new here and i hope that this question is posted here correctly.

I had some difficulty in answering some questions pertaining to the vapor-compression cycle and really hope that you guys could enlighten me. Thanks in advance!! ;D

Q1: when i conduct the experiment of fixing the condenser cooling water flow rate and vary the evaporator load voltage input (from 200 V to 180V), how do i explain the change in evaporator and condenser pressure? or the COP? do i need to explain them using the p-h diagram?

ps: from my lack of understanding, i could only guess the answer such that the evaporator pressure will decrease due to less cooling is needed for the load and thus less vapour is present in the evaporator, resulting in drop of pressure. <------ am i correct in some way? :P

again, thanks again in advance for the time.

[taz24]

<------ am i correct in some way? :P

again, thanks again in advance for the time.

You are correct in every way

A ph chart would plot the difference exactly but your uderstanding of the situation is correct.

If you lower the load on the evap the evap will get colder and therfore the pressure will lower. Conversly if you raise the load on the evap the pressure will rise. This remains the same as long as the compressor is pumping at a consistant rate.

Cheers taz.

[James W]

Thanks alot taz.. I was uncertain with this answer all the while~


Thanks with such a wonderful forum which enabled me to communicate with the expertise and enhance my understanding in refrigeration concepts.