# Find mass flow rate using heat differential

1. Apr 24, 2012

### mckray

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

An experimental power plant at the Natural Energy Laboratory of Hawaii generates electricity from the temperature gradient of the ocean. The surface and deep-water temperatures are 25°C and 7°C respectively.

The cold water that enters the plant leaves it at a temperature of 12°C What must be the flow rate of cold water through the system? Give your answer in kg/s & L/s.

dm/dt = ?

2. Relevant equations

W = QH - QC
e = 1 - TC / TH
cwater = 4190 J/kg*K

3. The attempt at a solution

I understand that it takes a certain amount of time to raise the water from 7°C to 12°C, but I don't know how to find that or how to relate it to a flow rate.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Dec 13, 2013

### Eagle's Wings

remember what you have and what you want to know. you have ΔT, c, and P (which is Q/t) and you want kg/s (which is mass/time)....i think there is an equation for that, do you remember it? remember, your answer is going to be in kg/s.

3. Dec 13, 2013

### SteamKing

Staff Emeritus
How much electrical power is the plant supposed to generate? That would seem to be a critical bit of information in determining how much flow is required.