Question

The owner of a small office building asked you to design the new air conditioning system for the building. The system cools the air supplied to the offices using a chiller (cold water refrigeration system). The water requirement for the evaporator in each floor is 18.2 mh. The velocity within the pipe must remain between 1.5 m/s and 2.5 m/s, to ensure the appropriate heat exchange process in the evaporators and minimize the noise. The material of the pipe is commercial steel Schd 40, and the available diameters are giving in table 1. The pipe length between each node (number points in the diagram) is 10 m. The pressure drop for each evaporator is 41368 Pa and for the refrigeration unit (Chiller) is 55158.2 Pa. As part of the design you need to specify the appropriate pipe diameter for each section, the pump power. Finally you need to specify the losses required in each of the valves to balance the system. The selection process needs to consider the costs of pipes and electricity. To estimate your electrical cost, use a value of 25 ckWh.

Answer 1

Here

?P=pressure difference across pump, Pa

Q=flow in m3/s

We consider maximum pressure drop for pump as than for loop 1-2-3-4-5-6-7-8-9-10-11-12-13-14-1.

The flow is difference branches will be balanced by introducing pressure drop through valves.

The balancing pressure is obtained by calculating the difference in pipe leg pressure drops between the highest pressure drop circuit and other circuits.

The result is presented below: