Consider operation of a single pass cross-flowheat exchanger with water (cp = 4193 J/kg·K) (mixed) andmethanol (cp = 2577 J/kg·K) (unmixed). Water entering andexiting the heat exchanger at 90°C and 60°C, respectively, isused to heat the methanol initially at 10°C. The overall heattransfer coefficient and the total heat transfer rate are estimatedto be 650 W/m2·K and 250 kW, respectively. In orderto achieve an effectiveness of at least 0.5, (a) what would be the mass flow rate of water and heat exchanger surface area?(b) If the mass flow rate of water is changed within 630% ofthat determined in part (a) with the same surface area (As),plot the variation of heat transfer rate, methanol exit temperature,overall heat transfer coefficient and the effectiveness ofheat exchanger with respect to change in the water flow rate.
Heat Exchangers
Heat exchangers are the types of equipment that are primarily employed to transfer the thermal energy from one fluid to another, provided that one of the fluids should be at a higher thermal energy content than the other fluid.
Heat Exchanger
The heat exchanger is a combination of two words ''Heat'' and ''Exchanger''. It is a mechanical device that is used to exchange heat energy between two fluids.
Consider operation of a single pass cross-flow
heat exchanger with water (cp = 4193 J/kg·K) (mixed) and
methanol (cp = 2577 J/kg·K) (unmixed). Water entering and
exiting the heat exchanger at 90°C and 60°C, respectively, is
used to heat the methanol initially at 10°C. The overall heat
transfer coefficient and the total heat transfer rate are estimated
to be 650 W/m2·K and 250 kW, respectively. In order
to achieve an effectiveness of at least 0.5, (a) what would be the mass flow rate of water and heat exchanger surface area?
(b) If the mass flow rate of water is changed within 630% of
that determined in part (a) with the same surface area (As),
plot the variation of heat transfer rate, methanol exit temperature,
overall heat transfer coefficient and the effectiveness of
heat exchanger with respect to change in the water flow rate.
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