Question

Fifty units in parallel of full tracking parabolic trough solar concentrator (PTC), is 1 m wide and 4 m long. A receiver suspended above the trough, consisting of a simple copper tube of 3.75 cm diameter coated with Ebanol-C (a = 0.9), which is covered with transparent Sunadex white crystal tube of 6 cm diameter (t = 0.915). The reflector is back silvered glass (p=0.9), If the PTC is operating with inlet and outlet temperatures of 70°C and 95°C respectively using water (cp = 4186 J/kg K), the direct normal intensity was 850 W/m² and the average overall heat loss coefficient of 4 W/m2.K, assume an ambient temperature of 25°C and. Calculate: The concentration ratio, The collection efficiency, The water flow rate/unit PTC The useful heat.

Answer 1

Concentration ratios Effective aperture area - Absorber Tube area 2) m- 0.06 24 9.10 = 49.) concentration ratio II) Nou as given in the question the incident radiation I 850W/m² area of Incidencez) x 4x50 2200

Area of collection tube - 60.06) X 200 m2 12 m² chence effective area Coo-12 a 188 so total e Energy incident 1888850 Want z 158, 800W Now coefficient of reflection of parabolic mirror is fro.ge so energy incident on tube is 159,800x o.9 21143,820 W Coefficient of transmittonce of londo Sunaides grass is T20-915 Iso Energy goes to o tube W inside = 143, 8ox 0.915 131 501583 Thermal Diffusivity of copper tube coating is a = 00.4

So het radiation going into tuorter inside after refletion is a) 131,595.340.9.11 118, 435.77 W The radiation is also directly incident on the collector sipe so the heat going the inside from that area con le written on (Area of pipe incident with Mouliation) & Tx L x 850 Whana 0.06x200 x 0.915x0.9 X 850 W 8399.7W 14 - Now total heat lost from the Areax ATX Overall heat 1 cofficient 180x0.06x/4x + 700 250 % bolt * Wouda 8670.8W

Total Sensible heatizoing inside 2 118,435177+8399.7 867080 S 118, 169.67 W total heat. I Mass flow rate of water 118, 164.67 M (PAT m 195-70 my n og 1.19 kg / seco H19 Rollen elo y lento verunit Efte 50 20.0226k alles Collection efficiency Geful heat A Incident heat 2 118, 164.67 on 850x200 0.695 Rg Alle

- Mass flow rate of water 1 118, 164. 67. m C AT -) en xul86x (95-70) m = 1.129 kg/sico m a ) 1: (29 0.0)26 byl seco ~ 22.6ign/euro sorunit PTC 50