Based on the analysis of computation methods and heat transfer processes of the parabolic trough receiver running in steady state, a two-dimensional empirical model was developed to investigate the thermal performance of heat loss of parabolic trough receivers under steady state equilibrium. A numerical simulation was conducted for the parabolic trough receiver involved in a literature. Comparisons between numerical and experimental results show that the empirical model is accurate enough and can be used to investigate the thermal performance of heat loss of parabolic trough receivers. The thermal performance of heat loss of UVAC3 and the new-generation UVAC2008 was investigated respectively. The simulation results show that selective coatings and annular pressure influence the thermal performance of heat loss of parabolic trough receivers greatly, wind velocity influences the thermal performance of thermal loss of parabolic trough receivers only a little in contrast with the emittance of selective coatings and air pressure in annular space. And the thermal performance of thermal loss of the new-generation parabolic trough receiver has been improved in a large amount.
Two counterexamples in Liu's comment on'Recent Progress in Thermodynamics of Radiation—Exergy of radiation,effective temperature of photon and entropy constant of photon'are analyzed and the incorrect applications of the related concepts are indicated.The similarities and differences between the concepts of the effective temperature of photon,the exergy of spectral radiation,the entropy constant of photon and the macroscopic concepts of temperature,exergy,and entropy are further discussed.The duality of radiant energy,micro-state quantum characteristic and macro-state thermal characteristic is presented.
CHEN ZeShao 1,MO SongPing 1,2 &HU Peng 1 1Department of Thermal Science and Energy Engineering,University of Science and Technology of China,Hefei 230027,China
