Chapter 11, Problem 11.53P

A shell-and-tube heat exchanger consists of 135 thin-walled tubes in a double-pass arrangement, each of12.5-mm diameter with a total surface area of $47.5{\text{ m}}^2$ .Water (the tube-side fluid) enters the heat exchanger at $15°C$ and $6.5\text{ kg/s}$ and is heated by exhaust gas enteringat $\text{200}°C$ and $5\text{ kg/s}$ . The gas may be assumed to have the properties of atmospheric air, and the overall heattransfer coefficient is approximately ${\text{200 W/m}}^2\cdot \text{K}$ .
(a) What are the gas and water outlet temperatures?
(b) Assuming fully developed flow, what is the tubeside convection coefficient?
(c) With all other conditions remaining the same, plotthe effectiveness and fluid outlet temperatures as afunction of the water flow rate over the range from $\text{6}$ to $\text{12 kg/s}$ .
(d) What gas inlet temperature is required for the exchanger to supply $\text{10 kg/s}$ of hot water at an outlet temperature of $\text{42}°C$ , all other conditions remaining the same? What is the effectiveness forthis operating condition?