Page 218 - Handbook of Energy Engineering Calculations

FIGURE 9 Pump and system characteristics for engine cooling

system. (Mechanical Engineering.)

Calculation Procedure:

1. Compute the cooling-water quantity required
The cooling-water quantity required is G = H/(500Δ t), where G = cooling-
water flow, gal/min; H = heat absorbed by the jacket water, Btu/h =
(maximum engine hp) [heat dissipated, Btu/(bhp · h)];Δ t = temperature rise

of the water during passage through the engine,°F. Thus, for this engine, G =
(402)(3500)/[500(10)] = 281 gal/min (17.7 L/s).

2. Choose the cooling-system valve and pipe size
Obtain the friction head-loss data for the engine, the heat exchanger, and the

three-way valve from the manufacturers of the respective items. Most
manufacturers have curves or tables available for easy use. Plot the head
losses, as shown in Fig. 8, for the engine and heat exchanger.
Before the three-way valve head loss can be plotted, a valve size must be

chosen. Refer to a three-way valve capacity tabulation to determine a suitable
valve size to handle a flow of 281 gal/min (17.7 L/s). Once such tabulation
recommends a 3-in (76.2-mm) valve for a flow of 281 gal/min (17.7 L/s).
Obtain the head-loss data for the valve, and plot it as shown in Fig. 8.