OCTOBER 19-20, 2012 - YMCA University of Science & Technology

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
Using the notation used to represent various stage points in GSHP system, the mass balance equation for
compressor can be expressed as
1 = 2 = r (5)
Assuming no heat loss , using the enrgy balance equation the work input to the compressor can be expressed as
Ẁ comp = r (h 2 -h 1 ) (6)
3.2 Condenser
Mass Balance for the refrigerant flow in the condenser can be denoted as
r = 2 = 3 (7)
Similarly the mass balance for air flow in the fan coil unit which is connected to the condenser for heat
extraction, can be expressed as
5 = 6 = w (8)
The energy balance for refrigerant and air side are given by
Q cond = r (h 2 -h 3 ) (9)
Q cond =Q fc = w C pw (T 5 -T 6 ) (10)
3.3 Throttling valve
The Mass Balance for the refrigerant flow in the throttling valve can be denoted as
r = 4 = 3 (11)
In the absence of heat loss the energy balance is
h 3 =h 4 (12)
3.4 Evaporator
The Mass Balance for the refrigerant flow in the Evaporator can be denoted as
r = 4 = 1 (13)
Similarly the mass balance equation for brine water flow through the bore heat exchanger which is coupled to the
evaporator for heat transfer, is given as
7 = 8 = bw (14)
The energy balance for Evaporator is given by
Q evap = r (h 1 -h 4 ) (15)
Q evap = Q gh (16)
3.5 Fan coil unit
The Mass Balance for the refrigerant flow in the fan coil unit can be denoted as
air, in = air, out = air (17)
Q fc = Q cond (18)
Q cond = Q gh (19)
3.6 Ground – heat exchanger
The Mass Balance for the refrigerant flow in the Ground – heat exchanger can be denoted as
7 = 8 = bw (20)
The energy balance for Ground – heat exchanger is given by
Q gh = bw C p.bw (T 8 -T 7 ) (21)
Q evap = Q gh (22)
3.7 Performance Parameter
The Performance parameter of a GSHP unit can be estimated using parameter as defined below
COP = ( Q cond / Ẁ comp ) (23)
Where Q cond is the heat transfer rate of the condenser, while Ẁ comp is rate of work input to the compressor.
The actual power input to the compressor may be computed as follows
69