However, the smaller the receiver tube diameter, the higher the pressure drop through the tube and the smaller the second law efficiency. For a 4.8 m diameter parabolic dish, the larger the receiver tube diameter and the smaller the mass flow rate through the receiver, the higher the receiver surface temperature and the less efficient the collector becomes. The inbuilt features allows a single PV module to charge the controller with autonomy of 2 days. This app allows the user an interactive augmented reality display to track the sun position and its path through the local sky for that GPS location/date, get exact times of sunrise, sunset. Receiver efficiencies are shown in terms of mass flow rate, receiver tube diameter, pressure drop, maximum receiver surface temperature and inlet temperature of the working fluid. For the BB10 and other Blackberry users, one example is the SunCalc Premium app, for which two screenshots are shown in Figure 1.25 (Crackberry, 2014). A method to determine the temperature profile and net heat transfer rate along the length of the receiver tube is presented. With the help of ray-tracing software, SolTrace, and receiver modelling techniques, an optimum receiver-to-concentrator-area ratio of A′ ≈ 0.0035 was found for a concentrator with 45° rim angle, 10 mrad optical error and 1° tracking error.
These high temperatures, however, have many disadvantages in terms of heat loss from the receiver, especially radiation heat loss. The Brayton cycle requires very high receiver surface temperatures in order to be successful. All these variables are considered in this paper. These variables include concentrator shape, concentrator diameter, concentrator rim angle, concentrator reflectivity, concentrator optical error, solar tracking error, receiver aperture area, receiver material, effect of wind, receiver tube diameter, inlet temperature and mass flow rate through the receiver. There are many different variables at play to model the air temperature increase of the air running through such a receiver. It is to be used in a small-scale solar thermal Brayton cycle using a micro-turbine with low compressor pressure ratios. Abstract: The first law and second law efficiencies are determined for a stainless steel closed-tube open rectangular cavity solar receiver.