Final Program EXPRES 2012 - Conferences

T ulf=32 º C, A - m =0.00162 kg/s, B - m =0.003 kg/s, C - m=0.005 kg/s, D - m =0.01 kg/s;(b) Change of local temperauter of the collector components in theflow direction: A – collector pipe , B – working fluid, C -surrounding layer of the collector, D – transparent coverFig 5 (a) shows the impact of the direct radiationintensity to the working temperature change in theflow direction, for the inlet fluid temperature T ul =32ºC and fluid flow 0.00162 kg/s. Fig 5. (b) depicts theimpact of the value of local inlet temperauter of thefluid to the local fluid temperature for the flow rateof 0.00162 kg/s and direct radiation of I b =950 W/m 2 .Fluid temperature in the axial direction Tf ( C )o3736353433320.0 0.2 0.4 0.6 0.8 1.0Axial direction z (m)ABCDFor the case of serial connection of six modules CPCreceiver, where the output from a previous entry infolowing collector, the results are shown in Fig 6(b).Fig 6(b) shows the impact of collector length to theoutput fluid temperature, for the searial connection ofsix CPC module(overall length L=6m), I b =950 W/m 2 ,input fluid temperature T ul =32 ºC and flow rate0.00162 kg/s where length increase compared to thecollector 1 m long, a higher output temperature isachieved. Serial connection a larger number ofmodules CPC receiver obtained a higher outlettemperature of working fluid. In the experiment wewere not able to connect the six units of CPC,but weassume that we would get significantly higher outlettemperature of working fluid, which of course opensthe possibility to prove it in the future.Instantaneous efficiency (%)535251504948474620 40 60 80 100 120 140 160oFluid inlet temperature Tf ( C )Fluid temperature ine the axial direction Tf ( C )o45 A403530250.0 0.2 0.4 0.6 0.8 1.0Axial direction z (m)Figure 5. (a)Impact of the direct radiation value to thelocal temperature in the flow directionA - I b =1000 W/m 2 , B - I b =900 W/m 2 , C - I b =800 W/m 2 , D -I b=700 W/m 2 ;(b) Impact inlet fluid temperature value to the local fluidtemperature in direction flow: A - T ulf=40 º C, B - T ulf=32 º C, C -T ulf=24 º C.Fig 6. (a) depicts the impact of inlet fluidtemperature to the current heat efficiency, for directradiation I b =950 W/m 2 and flow rate 0.00162 kg/s.The graphs shows that by raising inlet temperature ofthe fluid, heat efficiency drops. This is explained bythe fact that solar fluks and environment temperatureremain constant, and the diference between inlet fluidtemperature is reduced, thus usefull energy is reduced.BCFluid temperature in the axial direction Tf ( C )o65605550454035300 1 2 3 4 5 6 7Axial directionz (m)Figure 6 . Impact of the input fluid temperature value tothe current heat efficiency of the CPC collector(b) Impact of the length to the value of the outputtemperatureAn important feature of the programFORTRAN-77 is that it has a simple user interfacethat allows directinput from the keyboard of allparametersm of interest by the user. This opens widepossibilities of numericalmsimulations of realexperiments and detailed numerical analysis of theimpact of geometric and operating parameters onmechanism of transformation of solar energy into heatenergy.107