Energy and exergy analysis of solar hybrid adsorption refrigeration system

Figures & data

Figure 1 Schematic of the solar hybrid AR system.

Figure 2 Photograph of the system.

Table 1 Specifications of the main components of the solar AR system.

Component	Technical specifications
Condenser	Type: shell and coil
	Capacity: 200 W
	Water: cooled
	Material: copper
Evaporator	Type: shell and coil
	Material: copper
	Capacity: 150 W
Expansion device	Capillary tube
Adsorbent bed	Type: rectangular
	Size: 40 cm × 40 cm × 18 cm
	Material: stainless steel
Parabolic solar concentrator	Solar concentrator of area 3 m^2 made of stainless steel
Adsorbent	Activated carbon
	Type: granular
Adsorbate	Methanol

Figure 3 Cross-sectional view of adsorbent bed.

Table 2 The thermophysical properties of activated carbon.

Type	Granular
Grade	4 × 8
Particle size	0.25 mm
Surface area	1800 m^2 g^− 1
The effective thermal conductivity	0.2 W m^− 1 K^− 1
Specific heat	958 J kg^− 1 K^− 1
Porosity (%)	50

Table 3 Uncertainty of performance parameters.

Description	Total uncertainty (%)
COPcycle	± 6.04
Heat input to the system	± 1.09
Exergy loss of adsorbent bed	± 8.2
Exergy loss of condenser	± 5.45
Exergy loss of expansion device	± 4.8
Exergy loss of evaporator	±  5.45

Table 4 Collector–receiver circuit.

Sub-system	Energy received (kW)	Energy delivered (kW)	Energy loss (kW)	First law efficiency,
Collector	Qi	Qs
Receiver	Qs	Qu
Collector–receiver	Qi	Qu

Table 5 Refrigerator circuit.

Component	Energy analysis using Equations (1) and (2)
Condenser
Expansion device
Evaporator
Adsorbent bed

Figure 4 Thermodynamic equivalence of adsorption cycle.

Figure 5 Variation of solar radiation with time.

Table 6 The average values of performance parameters of the solar hybrid AR system.

Parameter	Value
COPcycle	0.196
Solar COP	0.075
Heating COP	0.187
SCP (W/kg)	47.83
Maximum COP	0.457

Table 7 Comparison of several typical studies by using activated carbon–methanol working pairs.

Heat source	COP	Investigators
Solar heat	0.196	This study
Solar heat	0.09–0.13	Butcher, Dind, and Pons (2003)
Solar heat	0.12	Boubakri (2003)
Solar heat	0.24	Leite and Daguenet (2000)
Solar heat	0.1–0.12	Sumathy and Li (1999)

Figure 6 Variation of COP with increase in evaporator loads.

Figure 7 Variation of combined COP with increase in evaporator loads.

Figure 8 Effect of driving heat source temperature on exergetic efficiency and COP.

Figure 9 Variation of desorbed refrigerant with desorption time.

Figure 10 Variation of water and adsorbent temperature with heating time.

Figure 11 Pressure transients in adsorbent bed with heating and desorption time.

Table 8 Energy balance for the complete system.

Sub-system	Energy received (kW)	Energy delivered (kW)	Energy loss (kW)	First law efficiency, (%)
Collector	2.192	1.176	1.016	53.4
Receiver	1.176	0.758	0.418	64.4
Collector–receiver	2.192	0.758	1.42	34.5
Refrigerator	0.758	0.150	0.608	19.7
Circuit overall system	2.192	0.150	2.402	6.84

Table 9 Second law analysis of refrigerator circuit.

Component	Irreversibility (exergy loss) (kW)	Second law efficiency (%)
Condenser	0.048	42.39
Expansion device	0.0128	79.89
Evaporator	0.0425	54.7
Adsorbent bed (thermal compressor)	0.1091	11.02

Figure 12 Grassmann (exergy flow) diagram for the solar AR system.

Table 10 Second law analysis of collector–receiver circuit.

Component	Exergy loss (kW)	Second law efficiency (%)
Collector	1.67	19.11
Receiver	0.34	19.2
Collector–receiver	1.99	3.76

Butcher, F., P. H.Dind, and M.Pons. 2003. “An Experimental Solar Powered Adsorptive Refrigeration Tested at Burkina-Faso.” International Journal of Refrigeration26: 79–86.

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