Mitsubishi Electronics PE-7MYC, PE-8MYC manual Efficiency Calculation, Calculation of net capacity

(Step-3) Calculation of net capacity

Based on the indoor conditioned temperature (WB,DB), designed outdoor temperature (DB), and the actual air flow obtained in Step-2, obtain the gross capacity from the gross capacity tables (pages 16~35). Then, calculate the net capacity from the formula below by using the fan motor input obtained in Step-2.

Net capacity (kW) = Gross capacity (kW) - Fan motor input (kW)

Example: PE-8MYC

Condition:

Indoor conditioned temp. : 26˚CDB, 19˚CWB

Designed outdoor temp. : 40˚CDB

Actual air flow : 77CMM

Fan motor input : 0.6kW (See P.11)

Calculation :

The sections of the gross capacity table applicable for the above conditions are shown right.

At 26˚CDB, 19˚CWB of Indoor,

Q = 21.3, SHC = 16.3, T/I = 8.3

		OUTDOOR DB˚C
INDOOR	INDOOR
		40.0
DB˚C	WB˚C	Q kW SHC kW SHF T/I kW

26 19 21.3 16.3 0.77 8.3

Factor for Various Air Flow

PE-8MYC-EU	AIR VOLUME	CMM	60	70	80
		L/S	1,000	1,167	1,330
COOLING	CAPACITY		0.976	1.0	1.025
	TOTAL INPUT		0.991	1.0	1.009
	SHC		0.963	1.0	1.044

Therefore, when air flow is 77(CMM)
Q = 21.3 ✕ (1+(1.025 - 1.0) ✕ 7/10*)	21.7(kW)
SHC = 16.3 ✕ (1+(1.044 - 1.0) ✕ 7/10*) 16.8(kW)
T/I = 8.3 ✕ (1+(1.009-1.0))✕7/10*)	8.4(kW)	Note * : 7/10 = (77-70)/(80-70)

Therfore, the net capacity is,

Net total cooling capacity = 21.7 (kw) - 0.6(kW) = 21.1 (kW)

Net sensible cooling capacity = 16.8 (kW) - 0.6 (kW) = 16.2 (kW)

2.Efficiency Calculation

•Refrigerant cycle energy efficienty

Gross total cooling capacity (kW)

(1) COP =

• System energy efficienty

Net cooling capacity (kW)

(1) COP =

Compressor input (kW)

Gross total cooling capacity (kW)

(2) ERR =

Total input (kW)

(2) ERR =

Compressor input (kW)

Net cooling capacity (kW)

Total input (kW)

1kW = 3412Btu/h

Notes: 1. COP : Coefficient of performance

2.EER : Energy efficiency ratio

3.Temperature condition of COP, EER (ARI Standard Ratings) Indoor entering air temp. : 80˚FDB (=27˚CDB), 66˚FWB(=19˚CWB) Outdoor entering air temp. : 95˚FDB (=35˚CDB)

4.Total input = Compressor input + Indoor fan motor input + Outdoor fan motor input (page 11).

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