Carrier 30XW325-400 Selection procedure, Performance data, Evaporator and Condenser Flow Rates

Selection procedure

Carrier’s packaged selection program provides quick, easy selection of Carrier’s water-cooled chillers. The pro- gram considers specific temperature, fluid and flow requirements among other factors such as fouling and alti- tude corrections.

Before selecting a chiller, consider the following points: Leaving water (fluid) temperature (LWT)

•The LWT must be at least 40 F (4.4 C) or greater.

•If the LWT requirement is greater than 60 F (15.5 C), a mixing loop is required.

Entering water (fluid) temperature (EWT)

•If the EWT requirement is greater than 70 F (21.1 C), a mixing loop is required. The EWT should not exceed 70 F (21.1 C) for extended operation. Pulldown can be accomplished from 95 F (35 C).

Evaporator flow rate or evaporator delta-T:

•The evaporator delta-T (EWT – LWT) must fall between 5 and 20° F (2.8 and 11.1° C) while still meeting the maximum entering requirements.

•For larger or smaller delta-T applications, a mixing loop is required. If the evaporator flow is variable, the rate of change of flow should not exceed 10% per minute. The loop volume in circulation must equal or exceed 3 gallons per nominal ton (3.2 L per kW) of cooling for temperature stability and accuracy in normal air condi- tioning applications. In process cooling applications, there should be 6 to 10 gallons per ton (6.5 to 10.8 L per kW). To achieve this loop volume, it is often neces- sary to install a tank in the loop. The tank should be baf- fled to ensure there is no stratification, and that water (or brine) entering the tank is adequately mixed with liq- uid in the tank. See Water Loop Volume in the Applica- tion Data section.

Evaporator pressure drop:

•A high evaporator pressure drop can be expected when the evaporator delta-T is low. A mixing loop can help to alleviate this situation.

•The three-pass evaporator option is recommended to increase performance when the evaporator delta T is high. This is particularly helpful with brine applications.

Condenser pressure drop:

•A high condenser pressure drop can be expected when the condenser delta-T is low. A one-pass condenser can help lower pressure drop.

Series chillers:

•One-pass heat exchangers can help lower pressure drop when heat exchangers are placed in series.

Water quality, fouling factor:

•Poor water quality can increase the required evaporator fouling factor.

•Higher than standard fouling factors lead to lower capacity and higher input kW from a given chiller size compared to running the same application with better water quality (and lower fouling factors).

Temperature reset:

•Return water (standard)

•Outside air temperature (standard)

•Space temperature (accessory sensor required)

•4 to 20 mA (requires an energy management module)

Demand limit:

•2-step (requires an energy management module)

•4 to 20 mA (requires an energy management module)

•CCN Loadshed

Performance data

EVAPORATOR AND CONDENSER FLOW RATES

			EVAPORATOR					CONDENSER					NOMINAL
		Leaving Fluid/Entering Fluid				Minimum Entering			Maximum Leaving
		Minimum		Maximum			Fluid			Fluid		Evaporator		Condenser
30XW UNIT		40 F (4.4 C)/		60 F (15.6 C)/		65 F (18.3 C)			118 F (47.8 C)*
		45 F (7.2 C)		70 F (21.1 C)
		Minimum		Maximum		Minimum			Maximum			Nominal		Nominal
		Flow Rate		Flow Rate		Flow Rate			Flow Rate			Flow Rate		Flow Rate
		GPM	L/s	GPM	L/s	GPM		L/s	GPM		L/s	GPM	L/s	GPM	L/s
	Two pass	411	25.9	1481	93.4	494		31.1	1974		124.5	790	49.8	987	62.3
325	One pass	790	49.8	3126	197.2	987		62.3	3290		207.6	790	49.8	987	62.3
	Three pass	247	15.6	987	62.3	—		—	—		—	790	49.8	—	—
	Two pass	433	27.3	1557	98.2	519		32.7	2076		131.0	830	52.4	1038	65.5
350	One pass	830	52.4	3287	207.4	1038		65.5	3460		218.3	830	52.4	1038	65.5
	Three pass	260	16.4	1038	65.5	—		—	—		—	830	52.4	—	—
	Two pass	486	30.7	1751	110.4	584		36.8	2334		147.3	934	58.9	1167	73.6
400	One pass	934	58.9	3696	233.1	1167		73.6	3890		245.4	934	58.9	1167	73.6
	Three pass	292	18.4	1167	73.6	—		—	—		—	934	58.9	—	—

*Maximum condenser fluid temperature shown for standard condensing option. Heat machine option may have leaving fluid temperatures up to 140 F (60 C).

15