1. Consider laminar, fully developed flow in a channel of constant surface temperature Ts. For a given mass flow rate and channel length, determine which rectangular channel, b/a = 1.0, 1.43, or 2.0, will provide the high- est heat transfer rate. Is this heat transfer rate greater than, equal to, or less than the heat transfer rate associ- ated with a circular tube?
2. You have been asked to perform a feasibility study on the design of a blood warmer to be used during the transfusion of blood to a patient. This exchanger is to heat blood taken from the bank at 10°C to 37°C at a flow rate of 200 ml/min. The blood passes through a rectangular cross-section tube, 6.4 mm X 1.6 mm, which is sandwiched between two plates held at a con- stant temperature of 40°C.
parts. The gallery dimensions are a = 90 mm and b = 9.5 mm, and the fluid flow rate is 1.3 X 10-3 m3/s. The coolant temperature is 15°C, and the mold wall is at an approximately uniform temperature of 140°C. a b Gallery coolant, m Alloy melt Mold body
To minimize corrosion damage to the expensive mold, it is customary to use a heat transfer fluid such as ethylene glycol, rather than process water. Compare the convec- tion coefficients of water and ethylene glycol for this application. What is the tradeoff between thermal perfor- mance and minimizing corrosion?