Feasibility study of a new concept of solar external receiver: Variable velocity receiver

Abstract

The deployment of new solar power tower plants mainly depends on becoming costcompetitive with traditional forms of electricity generation. The solar field represents around 40% of the solar power tower investment cost, thus the cost reduction of such subsystems is mandatory to achieve that goal. This reduction could be done by increasing the solar flux intercepted by the receiver, which would increase the peak flux. Therefore, new concepts of solar receivers are required to accommodate such high peak flux.The proposed receiver, which withstands high peak flux, consists on a Traditional External Tubular Receiver (TETR) equipped with valves that allow the division of each panel of the receiver in two independent panels, increasing the velocity of the heat transfer fluid in specific zones of the receiver. This receiver configuration, named Variable Velocity Receiver (VVR), avoids tube overheating. Moreover, this novel receiver allows more concentrated aiming strategies, which increases the optical efficiency of the solar field and permits to reduce the number of heliostats in the field. Given a specific generation capacity, the size of the solar field required by a VVR is 12.5% smaller in comparison to a TETR.Such efficiency improvement has a negligible effect in tube mechanical stresses; even though pressure drop and parasitic consumption of the power plant increase. This new receiver configuration also gains hours of operation, even in winter: in hours with low solar irradiance all the panels can be split in two, increasing the number of passes and the velocity of the heat transfer fluid and accomplishing the transition from laminar to turbulent regime. Therefore, this receiver is able to reduce the levelized cost of energy.

Thermo-mechanical modelling of solar central receivers: Effect of incident solar flux resolution

“…The lowest maximum wall temperature in the whole receiver corresponds to k=1.5 instead of k=1. Although, the spillage losses are lower in k=1.5 than in k=1 (higher average heat flux), the flux distribution in k=1.5 is more homogeneous than in k=1, see (Rodríguez-Sánchez et al, 2018), and then the peak flux and then the maximum wall temperature in the whole receiver are lower. For the receiver analysed and a given aiming factor, the CGM underestimates the maximum wall temperature and the thermal stresses of the whole reciever around 10 °C and 3MPa, respectively.…”

A review of steady-state thermal and mechanical modelling on tubular solar receivers

“…The bayonet design exhibits promising results when compared to conventional molten salt receiver tubes [68], with thermal efficiency improvements of 2% and maximum wall temperature reductions of > 100 • C reported. A variable velocity (VVR) molten salt cylindrical receiver concept is proposed by Rodríguez-Sánchez et al [72], with the thermal model presented by Ref. [68] used to investigate thermohydraulic performance.…”

An Investigation of the Optimum Solar Flux Distribution on a Large-Scale Particle Heating Receiver

“…Alternate methods of aiming (Garcí a et al, 2020;Acosta et al, 2021) 3. Modifying the heat transfer properties of the system by changing the operating conditions (Zhang et al, 2013;Rodríguez-Sánchez et al, 2018) Single point aiming strategy, which was first suggested by reference (Vant-Hull, 2002), is investigated by various researchers (Sanchez-Gonzalez et al, 2017;Garcí a et al, 2020). However, the flux profile produced by this singleparameter aiming strategy is rather irregular, with different amplitudes along the receiver height.…”