As stated at the beginning of the chapter, the radiation transfer method assumes isotropic radiation and uniform fluxes incident and leaving a surface. The isotropic assumption is necessary in order to remove the intensity, i, from the double integral that determines the radiation flux leaving a surface [equation (6.4)]. This results in the double integral […]

Consider the system shown in Figure 8.1 with the gap between the reflector and the PV arrays removed so that wE = wC3 = 10cm, wC1 = 6cm, wC2 = 9cm, and h = 0.2cm. Also, assume the same properties as used in Figure 8.2. Using the Mathematica program in Appendix F the efficiencies, temperature, […]

Combining a selective emitter with a back surface reflector (BSR) on the PV arrays is a method of spectral control that makes possible large cavity efficiency. A rare earth selective emitter provides large emittance for the range of wavelengths that are hc convertible by the PV arrays. Also, in the range Xg < X < […]

As already mentioned, the large value of the radiation flux incident on the filter-PV array means that a significant absorptance loss will occur even for small values of the filter spectral absorptance. Consider the interference-plasma filter presented in Chapter 4 (Figure 4.22). That filter has very low absorptance (« 0.01) at all wavelengths except in […]

The leakage of radiation from the optical cavity through the 0.05cm gap between the PV arrays and the reflector can be prevented by connecting the reflector to the PV arrays. Obviously, this will result in thermal conduction from the hot reflector to the cold PV arrays. However, this conduction loss can be minimized by using […]

The basic radiation transfer equation is given by equation (6.5), Qab = TabqoaFabAa W/nm (8.2) where Qab is the radiation power incident on area Ab that originates at area Aa. Also, xab is the transmittance of the media between Aa and Ab, qoa is radiation power per unit area per wavelength leaving Aa and Fab […]

Preceding chapters have concentrated on two objectives. The earliest chapters explained and quantified the performance of the major components of a TPV system. Later chapters developed the analysis to calculate the performance of a TPV system. Therefore, the major objective of this chapter is to describe the radiation transfer method for determining the performance of […]

1) for 0 < X < X& pC « 0 and pfFE, CFCE, ^ 1 2) for Xg < X < да, г2 « pf pj 7.2 Derive equation (7.34) for a cylindrical filter TPV system with a blackbody emitter from equation (7.33) using the following approximations. 1) for 0 < X < Хг, pC […]