Solar Collector Losses Summary - Revision history

WikiSysop: /* Introduction */

2009-02-01T22:20:36Z

Introduction

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	#Edge Lossses - 10% - from [[Solar_Collector_Calculations#Losses_due_to_edge_effects_only]] - about if we consider the 6 hours of highest sun during the day, or from 9:30 AM - 2:30 PM		#Edge Lossses - 10% - from [[Solar_Collector_Calculations#Losses_due_to_edge_effects_only]] - about if we consider the 6 hours of highest sun during the day, or from 9:30 AM - 2:30 PM
	#Reflection from collector tube glass - 4% loss		#Reflection from collector tube glass - 4% loss
			#Shading losses from collector tube - 1 slat will be covered by the shadow of the collector tube - at a time, for 6% loss (1 of 16 slats shaded)
	(total losses before collector tube are 15% = 6.8 kW)		(total losses before collector tube are 21% = 9.5 kW)

	#Radiation losses from collector tube - 7.5 kW with emissivity = .25 selective coating		#Radiation losses from collector tube - 7.5 kW with emissivity = .25 selective coating
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	We assume that all the remaining energy goes into heating the water in the collector tube.		We assume that all the remaining energy goes into heating the water in the collector tube.

	The sum of these losses is 21 kW, with 24 kW remaining, or 47% loss.		The sum of these losses is 24 kW, with 21 kW remaining, or 53% loss.

	For general purposes, we will say that the collector is slightly ~~over~~ 50% efficint.		For general purposes, we will say that the collector is slightly under 50% efficint.

	=Conduction Losses=		=Conduction Losses=

WikiSysop: /* Introduction */

2009-01-31T18:24:25Z

Introduction

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	#Absorptance losses at collector tube - 4 kW		#Absorptance losses at collector tube - 4 kW
	#Conduction losses of conductor tube - 2.7 kW		#Conduction losses of conductor tube - 2.7 kW

			We assume that all the remaining energy goes into heating the water in the collector tube.

			The sum of these losses is 21 kW, with 24 kW remaining, or 47% loss.

			For general purposes, we will say that the collector is slightly over 50% efficint.

	=Conduction Losses=		=Conduction Losses=

WikiSysop: /* Introduction */

2009-01-31T18:21:08Z

Introduction

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	#Reflection from collector tube glass - 4% loss		#Reflection from collector tube glass - 4% loss

	(total losses before collector tube are 15%)		(total losses before collector tube are 15% = 6.8 kW)

	#Radiation losses from collector tube - 7.5 kW with emissivity = .25 selective coating		#Radiation losses from collector tube - 7.5 kW with emissivity = .25 selective coating

WikiSysop: /* Introduction */

2009-01-31T18:20:03Z

Introduction

← Older revision		Revision as of 18:20, 31 January 2009
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	#Radiation losses from collector tube - 7.5 kW with emissivity = .25 selective coating		#Radiation losses from collector tube - 7.5 kW with emissivity = .25 selective coating
	#Absorptance losses at collector tube - 4 kW		#Absorptance losses at collector tube - 4 kW
	#Conduction losses of conductor tube -		#Conduction losses of conductor tube - 2.7 kW

	=Conduction Losses=		=Conduction Losses=

WikiSysop at 18:19, 31 January 2009

2009-01-31T18:19:42Z

@@ Line 12: / Line 12: @@
 #Absorptance losses at collector tube - 4 kW
 #Conduction losses of conductor tube -
 =Absorptance Loss=

WikiSysop: /* Introduction */

2009-01-31T18:14:28Z

Introduction

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	#Radiation losses from collector tube - 7.5 kW with emissivity = .25 selective coating		#Radiation losses from collector tube - 7.5 kW with emissivity = .25 selective coating
	#Absorptance losses at collector tube - 4 kW		#Absorptance losses at collector tube - 4 kW
			#Conduction losses of conductor tube -

	=Absorptance Loss=		=Absorptance Loss=

WikiSysop at 18:08, 31 January 2009

2009-01-31T18:08:48Z

← Older revision		Revision as of 18:08, 31 January 2009
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	#Edge Lossses - 10% - from [[Solar_Collector_Calculations#Losses_due_to_edge_effects_only]] - about if we consider the 6 hours of highest sun during the day, or from 9:30 AM - 2:30 PM		#Edge Lossses - 10% - from [[Solar_Collector_Calculations#Losses_due_to_edge_effects_only]] - about if we consider the 6 hours of highest sun during the day, or from 9:30 AM - 2:30 PM
	#Reflection from collector tube glass - 4% loss		#Reflection from collector tube glass - 4% loss

			(total losses before collector tube are 15%)

	#Radiation losses from collector tube - 7.5 kW with emissivity = .25 selective coating		#Radiation losses from collector tube - 7.5 kW with emissivity = .25 selective coating
	#Assume that the absorptance		#Absorptance losses at collector tube - 4 kW

			=Absorptance Loss=

			Assume that for the absorptance of 90% using [http://www.solec.org/solkotehome.htm#PRODUCT%20DESCRIPTION%20and%20FEATURES Solkote] selective coating, the 10% not absorbed is lost through conduction through the glass. The incoming radiation is the 45 kW of available radiation minus 15% of the collector losses, or 38 kW available. About 4 kW is lost due to imperfect absorption.

	=Radiation Loss Calculation=		=Radiation Loss Calculation=

WikiSysop: /* Introduction */

2009-01-31T18:02:10Z

Introduction

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	=Introduction=		=Introduction=

	When considering the overall performance of linear slat collectors for a linear Fresnel solar concentrator system oriented in the E-W direction, several losses must be considered. For the case of a 4:1 aspect ratio array, such as a 15 foot wide array that stretches for 60 feet in the E-W direction. For this case, if we use 6" slats, we can fit about 16 slats in this area, or a total of 480 square feet (45 sq meters) of solar intercept. We have about 5 kWhr/day per square meter in Maysville, Missouri - from [http://en.wikipedia.org/wiki/File:Us_pv_annual_may2004.jpg]. We summarize our losses. This includes air mass losses and averages over the seasons - because we are taking empirical data. We are assumining a collector tube with a single layer of insulating glass on the surface.		When considering the overall performance of linear slat collectors for a linear Fresnel solar concentrator system oriented in the E-W direction, several losses must be considered. For the case of a 4:1 aspect ratio array, such as a 15 foot wide array that stretches for 60 feet in the E-W direction. For this case, if we use 6" slats, we can fit about 16 slats in this area, or a total of 480 square feet (45 sq meters) of solar intercept. We have about 5 kWhr/day per square meter in Maysville, Missouri - from [http://en.wikipedia.org/wiki/File:Us_pv_annual_may2004.jpg]. We summarize our losses. This includes air mass losses and averages over the seasons - because we are taking empirical data. We are assumining a collector tube with a single layer of insulating glass on the surface. We are considering a case where we are letting the collector tube heat up to 650K.


	#Reflection losses from mirrors - 1%, assuming 99% reflective mirrors - and assuming that 4% reflection from glass is reflected back at the collector tube		#Reflection losses from mirrors - 1%, assuming 99% reflective mirrors - and assuming that 4% reflection from glass is reflected back at the collector tube
	#Edge Lossses - 10% - from [[Solar_Collector_Calculations#Losses_due_to_edge_effects_only]] - about if we consider the 6 hours of highest sun during the day, or from 9:30 AM - 2:30 PM		#Edge Lossses - 10% - from [[Solar_Collector_Calculations#Losses_due_to_edge_effects_only]] - about if we consider the 6 hours of highest sun during the day, or from 9:30 AM - 2:30 PM
	#Reflection from collector tube glass - 4% loss		#Reflection from collector tube glass - 4% loss
	#Radiation losses from collector tube -		#Radiation losses from collector tube - 7.5 kW with emissivity = .25 selective coating
			#Assume that the absorptance




	=Radiation Loss Calculation=		=Radiation Loss Calculation=

WikiSysop: /* Radiation Loss Calculation */

2009-01-31T17:58:24Z

Radiation Loss Calculation

← Older revision		Revision as of 17:58, 31 January 2009
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	*30 kW losses mean 2/3 of the incoming 45 kW of solar gain.		*30 kW losses mean 2/3 of the incoming 45 kW of solar gain.
	*Reduce this by selective coating of emissivity = 0.25 for [http://www.solec.org/solkotehome.htm#PRODUCT%20DESCRIPTION%20and%20FEATURES Solkote], and we get 7.5 kW of radiation ~~loass~~		*Reduce this by selective coating of emissivity = 0.25 for [http://www.solec.org/solkotehome.htm#PRODUCT%20DESCRIPTION%20and%20FEATURES Solkote], and we get 7.5 kW of radiation loss


			Setting the temperature to 650K gives us
	[[Category:Solar_Turbine]]		[[Category:Solar_Turbine]]

WikiSysop: /* Radiation Loss Calculation */

2009-01-31T17:50:10Z

Radiation Loss Calculation

← Older revision		Revision as of 17:50, 31 January 2009
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	*30 kW losses mean 2/3 of the incoming 45 kW of solar gain.		*30 kW losses mean 2/3 of the incoming 45 kW of solar gain.
	*Reduce this by selective coating of emissivity = .1		*Reduce this by selective coating of emissivity = 0.25 for [http://www.solec.org/solkotehome.htm#PRODUCT%20DESCRIPTION%20and%20FEATURES Solkote], and we get 7.5 kW of radiation loass


	[[Category:Solar_Turbine]]		[[Category:Solar_Turbine]]