Trane CCAF, CGWF manual Scroll Liquid Chiller Cgwf Selection Example

Selection Procedures

The chiller capacity tables on the following pages cover the most frequently encountered leaving water temperatures. For temperature drops other than 10°F [5.6°C], refer to Table SP-1, Performance Adjustment Factors, shown below.

Additional chiller selections and performance information can be obtained through your local Trane sales office.

To select a Trane water-cooled scroll chiller, the following information is required:

1.Design load in tons of refrigeration

2.Design chilled water temperature drop

3.Design leaving chilled water temperature

4.Entering condenser water temperature

Evaporator flow rate (gpm) can be determined by using the following formula:

gpm =	Tons x 24
	Chilled Water ￿T (F)

Condenser flow rate (gpm) can be determined by using the following formula:

gpm =

24 x (tons + (0.285 x compressor kW) Condenser Water ￿T (F)

Table SP-1. Performance adjustment factors

Fouling	Water		Evap.		Cond.
Factor	Delta T	Capacity	GPM	kW	GPM
	8	0.997	1.231	1.000	0.997
0.00010	10	1.000	1.000	1.000	1.000
	12	1.007	0.829	1.001	1.006
	14	1.012	0.714	1.001	1.010
	16	1.017	0.628	1.002	1.014

Note:

This selection procedure is for water only as the solution.

Scroll Liquid Chiller — (CGWF) — Selection Example:

Given:

System Load = 40 tons

Leaving Chilled Water Temperature (LCWT) = 44°F [6.7°C]

Entering Condenser Water Temperature (EWT) = 85°F [29.4°C]

Leaving Condenser Water Temperature (LWT) = 95°F [35°C]

Chilled Water Temperature Drop

=10°F [5.6°C]

1.From Table PD-1 (Performance Data), a CGWF 40 at the given conditions will produce 39.4 tons with a compressor power input of 30.3 kW and a unit EER of 15.6.

2.To determine the evaporator and condenser water pressure drops, the flow rates (gpm) must be determined. Using the formula above, this unit would require an evaporator flow rate of 95 gpm and a condenser flow rate of 115 gpm. (Compressor kW is found in the same table as the capacity.) The Evaporator Pressure Drop Curve, Chart PD-1, indicates that 95 gpm through a 40 ton evaporator results in a pressure drop of 13.8 feet of water. The Condenser Pressure Drop curve, Chart PD-2, indicates 115 gpm through a 40 ton condenser results in a pressure drop of 14 feet of water.

3.The final unit selection is:

—Quantity (1) CGWF 40

—Cooling Capacity = 39.4 tons

—Entering/Leaving Chilled Water Temperatures = 54/44°F [12.2/6.7°C]

—Chilled water flow rate = 95 gpm

—Evaporator water pressure drop = 13.8 feet

—Cooling water flow = 115 gpm

—Condenser water pressure drop = 14 feet

—Compressor power input = 30.3 kW

—Unit EER = 15.6

Compressor Chiller – (CCAF) – Selection Example:

Select the unit for the following conditions:

A compressor chiller is required to produce 45 tons when matched with an air-cooled condenser. The leaving chilled water temperature is 44°F [6.7°C]. The evaporator temperature differential is 10°F [5.6°C]. The ambient temperature is 95°F [35°C].

1.Select the nominal unit size. The performance data is tabulated by leaving chilled water temperature. For example, the standard unit capacities at 44°F [6.7°C] leaving chilled water temperature are found on page 21. The system that best meets the tonnage requirement is a CCAF 50 matched with a CAUC C50. The unit capacity is 47.1 tons with a kW input of

56.3.The compressor chiller EER is

2.Calculate the required chilled water flow rate.

3. gpm =	Tons x 24
	Chilled Water ￿T (F)
From this example,
gpm =	47.1 x 24 = 113
	10

4.Determine the evaporator water pressure drop. The evaporator water pressure drop is located on page 22. Entering the evaporator chart at 113 gpm, the pressure drop for a CCAF 50 evaporator is 7.9 feet.

5.Unit Selection

The above procedure shows the proper selection for this example is a CCAF 50 with a CAUB C50 condenser operating as follows:

—Capacity = 47.1

—Entering/leaving chilled water temperature = 54/44°F [12.2/6.7°C]

—Chilled water flow rate = 113 gpm

—Evaporator water pressure drop = 7.9 feet

—Compressor power input = 56.3

—Unit EER = 10.0

CG-PRC012-EN 15