Jun Sui

Prototype of Middle-Temperature Solar Receiver/Reactor With Parabolic Trough Concentrator

This paper manufactured an original middle-temperature solar receiver/reactor prototype, positioned along the focal line of one-axis parabolic trough concentrator representing the development of a new kind of solar thermochemical technology. A 5 kW prototype solar reactor at around 200-300 degrees C, which is combined with a linear receiver was originally manufactured. A basic principle of the design of the middle-temperature solar reactor is identified and described. A representative experiment of solar-driven methanol decomposition was carried out. Experimental tests were conducted from 200 degrees C to 300 degrees C under mean solar flux of 300-800 W/m(2) and at a given methanol feeding rate of 2.1 L/h. The conversion of methanol decomposition yielded up to 50-95%, and the efficiency of solar thermal energy conversion to chemical energy reached 30-60%. The experimental results obtained here prove that the novel solar receiver/reactor prototype introduced in this paper can provide a promising approach to effectively utilize middle-temperature solar thermal energy by means of solar thermochemical processes.

Mechanism of upgrading low-grade solar thermal energy and experimental validation

Solar thermochemical processes inherently included the conversion of solar thermal energy into chemical energy. In this paper a new mechanism of upgrading the energy level of solar thermal energy at around 200 degrees C was revealed based on the second law thermodynamics and was then experimentally proven. An expression was derived to describe the upgrading of the energy level from low-grade solar thermal energy to high-grade chemical energy. The resulting equation explicitly reveals the interrelations of energy levels between middle-temperature solar thermal energy and methanol fuel, and identifies the interactions of mean solar flux and the reactivity of methanol decomposition. The proposed mechanism was experimentally verified by using the fabricated 5 kW prototype of the receiver/reactor The agreement between the theoretical and the experimental results proves the validity of the mechanism for upgrading the energy level of low-grade solar thermal energy by integrating clean synthetic fuel. Moreover the application of this new middle-temperature solar/methanol hybrid thermochemical process into a combined cycle is expected to have a net solar-to-electric efficiency of about 27.8%, which is competitive with other solar-hybrid thermal power plants using high-temperature solar thermal energy. The results obtained here indicate the possibility of utilizing solar thermal energy at around 200 degrees C for electricity generation with high efficiency by upgrading the energy level of solar thermal energy, and provide an enhancement to solar thermal power plants with the development of this low-grade solar thermochemical technology in the near future.

Experimental Investigation of a Middle-and-Low Temperature Solar Receiver/Reactor Prototype

This paper designed and manufactured a 5-kW middle-and-low temperature solar receiver/reactor prototype at around 200°C–300°C, representing the development of a new kind of solar thermochemical technology. A representative experiment of solar-driven methanol decomposition was carried out. A specific equation of interrelationships among solar radiation, the kinetics of the middle-and-low temperature solar thermochemical reaction, and the diameter of the reactor tube is derived. The conversion of methanol decomposition yielded up to 50%–95% and the efficiency of solar thermal energy converted into chemical energy reached 30%–60%. The experimental results obtained here proves that the novel solar receiver/reactor prototype can provide a promising approach to effectively utilize the middle-and-low temperature solar thermal energy by means of solar thermochemical processes.