Abstract
An experimental platform was designed and built for testing the thermal performance of a water/steam cavity receiver. The experimental platform was utilized to investigate the start-up performance and operation characteristics of the receiver. The electrical heating mode was chosen to simulate the non-uniform distribution of heat flux on the surface of absorber tubes inside the cavity. During start-up the temperature rise rate and the mass flow rate are considered as control variables. A couple of start-up curves under different working pressures were finally obtained. The results showed that the receiver performed at relatively low thermal efficiencies. The main reason for the low thermal efficiency was attributed to the low steam mass flow rate, which causes a high proportional heat loss. In order to study the relationship between thermal efficiency and mass flow rate, a computational model for evaluating the thermal performance of a cavity receiver was built and verified. This model couples three aspects of heat transfer: the radiative heat transfer inside the receiver, the flow boiling heat transfer inside the absorber tubes and the convection heat transfer around the receiver. The water/steam cavity receiver of the experimental platform was studied numerically. The curve of thermal efficiency versus mass flow rate was obtained to show that the thermal efficiency increases with increasing mass flow rate within a certain range, and the increase is more remarkable at low mass flow rates. The purpose of the present study was to determine an appropriate mass flow rate for the receiver of the experimental platform to ensure its efficient operation.
Highlights
As problems of energy shortage and environment pollution become more and more serious, clean and renewable energy has been of particular concern and studied all over the World
A couple of experiments were conducted to study the thermal performance of the receiver during start-up processes under different target pressures
The thermal performance of the water/steam cavity receiver shown in Figure 2 during steady operation was studied numerically in the present study
Summary
As problems of energy shortage and environment pollution become more and more serious, clean and renewable energy has been of particular concern and studied all over the World. Solar energy is a kind of non-polluting renewable energy and can be obtained for free, so it has been used more and more extensively. The utilization of solar energy for power generation is usually realized by adopting three primary technologies. Wang [1] reported that the tower type solar power technology has better commercial prospects than those of trough type and dish type solar power technologies in respect of large-scale power generation. The equipment cost of tower type solar power system is much lower than that of dish type and slightly higher than that of trough type, and the equipment cost will be further reduced in larger scale power generation. The equipment cost of tower type systems mainly consists of the costs for the heliostat field and the receiver, and the cost of the receiver accounts for
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