A one-pass condenser-heat exchanger, shown in the sketch, has 64 tubes arranged in a square array with 8 tubes per line. The tubes are 1.22 m long and are made of copper with an outside diameter of 1.27 cm. They are contained in a shell at atmospheric pressure. Water flows inside the tubes whose outside wall temperature is 98°C. Calculate (a) the rate of steam condensation and (b) the temperature rise of the water if the flow rate per tube is 0.0454 kg/s.
GIVEN
? One-pass condenser heat exchanger with 64 tubes in a square array
FIND
(a) Rate of steam condensation
(b) Water temperature rise
SKETCH
PROPERTIES AND CONSTANTS
From Appendix 2, Table 13, the properties of saturated water at the film temperature (100 + 98)/2 = 99°C are
Wall temperature= 98°C
Saturation temperature = 100°C
Tube OD= 0.0127 m
Tube length = 1.22 m
Water flow rate= 0.0454 kg/s
From Equation (9.24), we can obtain the average heat transfer coefficient
where
and
Neglecting the vapor density compared to the liquid density, the quantity in the right bracket in the equation for the heat transfer coefficient is
so
The tube surface area is
The rate of heat transfer is therefore
(a) The flow rate of condensate is then
The heat transfer per tube is 83,688/64 W = 1308 W and this must equate to the increase in sensible heat in the cooling water, giving for the water temperature rise
(b)
You might also like to view...
The block shown is pulled across the horizontal surface at a constant speed by the force shown. If M = 5.0 kg, F = 14 N and ? = 35°, what is the coefficient of kinetic friction between the block and the horizontal surface?
A. 0.44 B. 0.33 C. 0.38 D. 0.28 E. 0.17
When a contracting hot ball of stellar gas spins into a disk shape, it cools faster due to
A) increased convection currents. B) increased radiation transfer. C) decreased insulation. D) increased surface area to volume. E) eddy currents.
Which of the following best describes how a small saltwater spill should be cleaned up in the elementary classroom?
a. Allow the spill to spread so that the water can quickly evaporate, then sweep up the salt b. Wipe up the spill with paper towels from the outer edge toward the center to minimize the spread of the spill c. Add water to dilute the salt water and increase the volume of the spill to ensure that all the students can help wipe up the spill d. Use the classroom sponge to absorb the spill, then squeeze out the salt water into its original container so that it can be reused
The three types of plate boundaries are convergent, ______________, and transform boundaries
Fill in the blank(s) with correct word