A shell and tube heat exchanger must be designed to heat 2.5 kg/s water from 15 to 85 degrees celsius. The heating is to be accomplished by passing hot engine oil, which is available at 160 degrees celsius, through the shell side of the exchanger. The oil is known to provide an average convection coefficient of h0 = 400 W/mK on the outside of the tubes. Ten tubes pass the water through the shell. Each tube is thin-walled, of diameter D = 25 mm, and makes eight passes through the shell.
If the oil leaves the exchanger at 100 degrees celsius, what is its flow rate? How long must the tubes be to accomplish the desired heating?

When at a point two solid phase changes to one solid phase on cooling then it is known as a) eutectoid point b) eutectic point c) peritectic point d) peritectoid point

The mass flow rate of the fluid remains constant in all steady flow process. a)- true b)- false

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?