# Total massflow through heat exchanger

I am working on a project and I stumbled on a problem. The project is to design a heat pump to replace the old system (actual problem, not some homework problem). There are 100 or so induction units which heat and cool rooms in an office building. From the technical specs and some calculations I have found that the mass flow of water needs to be 0.1 L/s per induction unit. Now my question is how would I find out what the mass flow through the heat exchanger in the heat pump should be. The one which cools the water.

My first guess was to multiply 0.1 L by 100 but that gives me 10 liters per second through the heat exchanger which sounds like a LOT.

I then had the idea that the units are connected in parallel to the main water pipe, which would make sense; you don't want to send out warm water into the same piping onto the other induction unit. Perhaps that plays a roll in the amount of water.

Further specs and numbers which are probably not necessary:

• 175kW total cooling capacity needed in the summer
• 900W capacity per induction unit.
• Primary air quantity: 30L/s (air injected into unit to begin air flow)
• Secondary air temp: 24 C (air temperature in the room which is circulated through unit)
• Water temperature: 12 C (water temp after cooled in heat pump)

The refrigerant has not been chosen yet.

Any form of help would be greatly appreciated

-
Hard to understand without a sketch. Do a complete mass- and energy balance of the heat exchanger and see where it leads you. –  mart May 13 '13 at 9:56