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471-2004-1-Concentrating collector-Serkan Kapucu

Dishengine systems require the development of at

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Unformatted text preview: lopment of low cost heliostats. Dish/engine systems require the development of at least one commercial engine and the development of a low cost concentrator [4]. concentrator [4]. Table 5.1 highlights the key features of the three solar technologies. Parabolic Trough Parabolic Dish/Engine Power Tower Size 30-320 MW 5-25 kW 10-200 MW Operating Temperature Operating (ºC/ºF) (ºC/ºF) 390/734 390/734 750/1382 750/1382 565/1049 Annual Capacity Factor Annual 23-50 % 23-50 25 % 20-77 % Peak Efficiency 20%(d) 20%(d) 29.4%(d) 29.4%(d) 23%(p) Net Annual Efficiency Net 11(d)-16% 11(d)-16% 12-25%(p) 7(d)-20% Commercial Status Commercially Scale-up Commercially Prototype Demonstration AvailableDemonstration AvailableDemonstration Technology Technology Development Risk Development Low High Medium Storage Available Limited Battery Yes Hybrid Designs Yes Yes Yes Cost USD/W 2,7-4,0 1,3-12,6 2,5-4,4 (p) = predicted; (d) = demonstrated; Table 5.1 Key features of the three solar technologies [4]. 6. Calculations 6. Heat from a solar collector may be used to drive a heat Heat engine operating in a cycle to produce work. A heat engine may be used for such applications as water pumping and generating electricity. pumping The thermal output Qout of a concentrating collector operating at temperature T is given by operating Qout = F'[gamma.Ainqin - U.Arec(T - Ta)], )], Ain : the area of the incident solar radiation (m2). Arec : the area of the receiver (m2) gamma:optical efficiency qin : the incident solar irradiation (W/m2) Ta :the ambient temperature (°C) U :the heat loss coefficient (W/m2K) F’ :collector efficiency factor The quantity Ain/Arec is called the concentration ratio. concentration High concentration ratios are obtained by making Ain the High area of a system of mirrors designed to concentrate the solar radiation received onto a small receiver of area Arec. solar Heat losses from the receiver are reduced by the smaller size of the receiver. Consequently, high concentration ratios give high collector temperatures. The...
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