A counter-flow heat exchanger has a heat transfer area of 5 m² and an overall heat transfer coefficient of 200 W/(m²·K). The hot fluid cools from 120 to 80 °C and the cold fluid heats from 25 to 55 °C. Find the heat transfer rate Q̇.
In a counter-flow heat exchanger the hot fluid cools from 115 to 70 °C while the cold fluid heats from 10 to 90 °C. Find the log-mean temperature difference ΔTlm.
A shell-and-tube heat exchanger (one shell pass, two tube passes) must transfer 300 kW. The hot fluid cools from 100 to 85 °C and the cold fluid heats from 25 to 60 °C. The LMTD correction factor for this arrangement is F = 0.9, and U = 500 W/(m²·K). Find the heat transfer area A needed.
In a condenser, steam condenses at a constant 140 °C on the outside of the tubes. Cooling water (0.5 kg/s, cp = 4.18 kJ/(kg·K)) flows through the tubes and heats from 30 to 65 °C. The overall heat transfer coefficient is 2000 W/(m²·K). Find the heat transfer area A needed.
Hot oil (0.5 kg/s, cp = 2.5 kJ/(kg·K)) cools from 85 to 55 °C in a counter-flow exchanger. It heats 3 kg/s of water (cp = 4.18 kJ/(kg·K)) that enters at 25 °C. With U = 200 W/(m²·K), find the heat transfer area A needed.
In a parallel-flow double-pipe heat exchanger, hot oil (0.3 kg/s, cp = 2.3 kJ/(kg·K)) flows in the inner tube and cools from 140 to 60 °C. Water (0.5 kg/s, cp = 4.18 kJ/(kg·K)) in the annulus enters at 15 °C. The inner tube has a diameter of 32 mm, and U = 200 W/(m²·K) is based on this diameter. Find the tube length L needed.
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