Answer Happy

(a) When the system is filled (at 35°C ambient temperature) it is desired to have a pressure
of 70 kPa at the highest point in the system which will reduce to 35 kPa when the water
temperature reduces to 7°C.
(b) What operating pressures (p1, p2) should the expansion tank be designed for? What
pump head is required?
(c) With the pump off and a cold (7°C) system, what is the pressure at the pump suction?
The pump discharge?
(d) With the pump on and a cold (7°C) system, what is the pressure at the pump suction?
The pump discharge?
(e) “Engineers considered chilled water system is a closed-loop system. Pipe and pump
design need not to consider static pressure head”. Based on the above calculation, comment
whether this statement correct or not.
In a chilled-water system, the pump is located in a basement equipment room with the expansion tank connected to the pump suction. The pump is the lowest point in the system and the highest point is a pipe in the penthouse, which is 50m above the pump. The dynamic head losses in the system are: Table A3 Head loss in pipes Piping and fittings 10m Chiller 6m Control valve 3m Cooling coil 4m (a) When the system is filled (at 35°C ambient temperature) it is desired to have a pressure of 70 kPa at the highest point in the system which will reduce to 35 kPa when the water temperature reduces to 7°C. (b) What operating pressures (p1, p2) should the expansion tank be designed for? What pump head is required? (c) With the pump off and a cold (7°C) system, what is the pressure at the pump suction? The pump discharge? (d) With the pump on and a cold (7°C) system, what is the pressure at the pump suction? The pump discharge? (e) "Engineers considered chilled water system is a closed-loop system. Pipe and pump design need not to consider static pressure head". Based on the above calculation, comment whether this statement correct or not.