# Homework Help: Missing Assumption/Information? (HVAC/R)

1. Aug 19, 2013

### cmmcnamara

1. The problem statement, all variables and given/known data

A refrigeration plant is rated at 1,200,000 Btu/hr with a cooling range of 10°F and a cold water temperature of 80°F. What is the maximum wet-bulb temperature allowable for 240 or 320 gpm?

2. Relevant equations

3. The attempt at a solution

I am not really sure where to even start this problem. I've poured over this problem multiple times for the last couple weeks but I can't seem to figure out what to do here. I've done the basic steady state mass flow balances on the air and water flows but without any state information given for the air I'm not sure how to get to an answer without making quite a few assumptions.

Things I do realize:

1) It asks for a maximum allowable wet bulb temperature which means that it must be a constant through out the process. This also indicates that the process must be cooling with humidification or heating with dehumidification. Therefore the process must be cooling with dehumidification (evaporative cooling??).

That's really about it. If I try to use the total heat rating to find SHR, that would rely on me assuming all of the inlet water gets transferred to the air (which is insane at those flow rates). Can anyone help me even get started here? I can't think of a valid assumption that could help me solve.

Thanks ahead of time for anyone's help.

2. Aug 20, 2013