Hello, here's a challenging heat transfer problem for me.
The heat exchanger evaluated in class on Wednesday, December 6 is a concentric tube unit measured for counter-flow. The temperature profile shown below shows the four water temperatures over the extended period of testing. The cold water flows through the annulus.
1200 Time [seconds]
1400
The vertical line is shown on the figure. The flow of cold water was measured.
Vcote = 0.1906 L/s
The hot water flowed through the center (copper pipe) in counter-flow configuration. At 400 seconds into the test, the four water temperatures and associated properties are:
Tncas = 50.0°C
Thtt = 48.1°C
TnMer = 20.9°C
Ti = 18.7°C
Pwwc = 998.0 kg/m
Pwxwc = 988.5 kg/m³
= 4180 kg-
PLUg d oe, dmin e b The mass flow of hot water.
c The UA value of the heat exchanger.
Part 2: The counter-flow heat exchanger has the following physical characteristics:
Inside pipe: Copper ID = 1.436 in. OD = 1.500 in. L = 30 in. (length)
Outside pipe: PVC ID = 2.067 in. OD = 2.375 in. L = 30 in. (length)
Using these parameters, perform the following steps and calculations:
a Sketch the heat transfer network between the hot fluid and the cold fluid.
b Determine the heat exchanger area based on the inside heat transfer surface: A.
c Determine the heat exchanger area based on the outside heat transfer surface: A.
Use an appropriate Nusselt relation to estimate the forced convection coefficient on the inside heat transfer surface: h.
Use an appropriate Nusselt relation to estimate the forced convection coefficient on the outside heat transfer surface: h.
Based on the above results (a, b, c, d, e), estimate the overall UA value of the heat exchanger.
