# Homework Help: Flat Plate Heat Exchanger. Find average convection HT coefficient

1. Sep 18, 2011

### cheme333

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

In this flat plate heat exchanger, rippled plates (0.3 m thick each) create channels that allow heat transfer between a hot and a cold fluid. Conduction occurs then from the heat temperature difference between the two fluids while convection occurs as the fluids move faster and turbulence occurs. The temperature distribution across one of the rippled plates at a certain instant of time is T(x) = a + bx + cx2, where T is in Kelvin and x is in meters, a = 200K, b = -200K/m, and c = 30K/m2. The material the plates are made of has a thermal conductivity of 1W/mK. Find the average convection heat transfer coefficient over time if the coldest surface of the middle plate is exposed to a fluid at 100K.

2. Relevant equations

I'm assuming all I will need is the heat transfer equations:

qconv = h(Ts - T$\infty$)

qcond = -k (dT/dx)

3. The attempt at a solution

I'm not sure where to begin. I have assumed that the conduction flows from the hot fluid to the cold fluid and the convection occurs from the turbulence between the plates, but I do not know how to relate the two to solve for h.

Can someone offer any help?

Thanks.

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