Dimplex ST0133 technical manual η = η

Technical manual

										SOLAR
η = η	0	− a	⋅	tm − ta	− a	2	⋅	(tm − ta )2		[1]
		1		G					G
Where:				η	[-]					thermal collector efficiency
				η0	[-]					optical collector efficiency/zero loss coefficient
				a1	[W/m²/K]					linear heat loss coefficient
				a2	[W/m²/K²]					squared heat loss coefficient
				G	[W/m²]					global incident radiation
				tm	[°C]					collector middle temperature
				ta	[°C]					collector ambient temperature

		9
		7
		6
1		5
		8
2
	3	4

Figure 9 – SOLC220 heat loss modes

The collector heat loss front (7) and collector heat loss back (8) are dependant on the operating conditions of the solar thermal collector, i.e. primarily on the temperature difference between the collector module and the ambient air and wind speed. Applying equation 1 to the Dimplex SOLC220 collector the graph shown in Figure 10 can be de- rived.

Page 12 of 72

ST0133 – A 02/09