Figure 1.1

Tower

Schematic

Piping

Diagram

CAE-464 MTRP 3

95 oF

85 oF

78 oF EWB

12 ft.

Problem 1Piping and Pumping

Given:

A 1000 ton refrigeration system is provided with a cooling tower and associated condenser water piping and pumping system.

The condenser water is cooled from 95 F to 85 F with 78 F WB air

The tower schematic piping diagram is shown in Figure 1.1

The condenser water flow rate is based on three gpm of condenser water per ton

The condenser water velocity is nominally eight feet per second.

The system is provided with two 50% capacity pumps and the suction and discharge pipe sizes and as shown.

The pump curve is shown on Figure 1.2

The breakdown of water flow paths and components is shown in Table 1.1

CAE-464 MTRP 4

Problem 1Piping and Pumping

Find:

A. Determine to remaining even pipe sizes in the system (Schedule 40, steel)

B. Calculate the system head requirements (Pipe friction factor = 0.02). Strainer data is shown in Figure 1.3, Triple Duty Valve data is shown in Figure 1.4

C. From the pump curve, determine the appropriate impeller size of each pump (Use the defined impeller sizes shown on the pump curve)

D. Develop a new curve showing the performance of one pump and two pumps running

E. Determine the system resistance curve accounting for the static head

F. Plot this system resistance curve on the combined pump curves. Identify the duty point on the curve

G. Determine the flow rate and head of one pump running

H. Determine the net positive suction head NPSH available and the NPSH required for the pumps

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Figure 1.2Pump Curve

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Figure 1.3Strainer Curve

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Figure 1.4Triple Duty Valve

Use 100 % Curve

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1.11.21.31.4