Primary or secondary VFD? 1

[cleanandsolar]

Greetings,

I am working on a energy conservation study and plan on installing VFDs on chilled water pumps that serve absorption chillers/AHUs. I think that the vfd should be installed on the secondary loop, my boss says it does not matter and is planing on installing them on the primary loop. Is there a preferable setup or can you install a vfd on any old loop you want(the loop with the largest hp motor)?

Thanks for your input.

 

[quark]

Generally flowrate through a chiller is always kept constant. Manufacturers strongly suggest it and bear no responsibility for the consequences. At one time I really fought with York but with little success. Conceptually I didn't find any problem, but this is democracy. There are no installations of variable pumping system for primary loop as far as my knowledge is concerned. Anyhow I appreciate your boss.

A standard practice is to apply variable pumping system to the secondary loop.

Balancing an absorption system is very difficult and you may end up with dry condenser or concentration of strong solution may increase because of reduced evaporation. You should take care of crystallization in low temperature heat exchanger.

As far as vapor absorption system is concerned, I don't take a chance.

Note: VSD will give you better result not if your motor HP is high but if your system volume flow requirement is variable.

ITT Bell&Gossett and Danfos are the best for chilled water variable speed systems. It is better to take their advice.

Regards,