Experimental testing of a small-scale solar thermal Brayton cycle recuperator
16th International Heat Transfer Conference (IHTC-16), 2018
The open Brayton cycle with open cavity receiver utilises a parabolic dish to concentrate solar i... more The open Brayton cycle with open cavity receiver utilises a parabolic dish to concentrate solar irradiance so that it may be captured by the working fluid (air). The cycle has been analysed and optimised to work with a simple receiver so that complexity and cost may be reduced. To maintain sufficient cycle effectiveness, a large efficient recuperator has to be implemented to allow for the high temperatures in order of 1000 K needed by the Brayton cycle. The proposed micro-turbine, an automotive turbocharger, cannot operate at high pressure ratios. The recuperator allows for lower pressure ratios to be considered. The purpose of this research is to test a design for a low-pressure and high-temperature recuperator that can be implemented within the solar Brayton cycle, and can be locally manufactured for a relatively low cost, as no current solution for such a cycle exists. Current solutions involve complex designs, expensive manufacturing processes and permanent joining methods that would eliminate the possibility for inspection and maintenance. The key element in the proposed design would see a high temperature sealant being used along with a clamped plate heat exchanger layout, in place of welding, allowing for ease of assembly as well as the ability to dismantle the unit for inspection. To ascertain the possibility of implementing the design, the recuperator was first modelled and shown to adhere to the necessary criteria. Results from the theoretical model show that at the proposed cycle conditions the recuperator plate bank would consist of 350 channels with an effectiveness of 90% and a total pressure drop of 3.49 kPa. A small scale model of the recuperator was constructed and tested, using both in-stream and surface thermocouples. Due to combustion issues with the LPG, the data was slightly skewed, however enough results were attained to show that the design could prove effective with a few modifications and further testing, and that the high temperature sealant works well with the clamped plate design.
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Papers by Josua P Meyer
past. In this paper, we address the fundamental question of what the size of the heat exchanger
should be, in addition to what architectural features it should have. The answer to the size question
follows from the tradeoff between (1), the useful power lost because of heat transfer and fluid flow
and (2), the power destroyed during transportation, manufacturing, and maintenance. Changes in
heat exchanger size induce changes in the opposite sign in the power requirements (1), and (2).
This fundamental tradeoff regarding size is illustrated by considering one side of a heat exchanger
(one flow passage) in laminar flow and in fully rough turbulent flow, with several duct cross
sectional shapes and arrays of channels in parallel. The size tradeoff is present in heat exchanger
applications across the board, from vehicles to stationary power plants.
past. In this paper, we address the fundamental question of what the size of the heat exchanger
should be, in addition to what architectural features it should have. The answer to the size question
follows from the tradeoff between (1), the useful power lost because of heat transfer and fluid flow
and (2), the power destroyed during transportation, manufacturing, and maintenance. Changes in
heat exchanger size induce changes in the opposite sign in the power requirements (1), and (2).
This fundamental tradeoff regarding size is illustrated by considering one side of a heat exchanger
(one flow passage) in laminar flow and in fully rough turbulent flow, with several duct cross
sectional shapes and arrays of channels in parallel. The size tradeoff is present in heat exchanger
applications across the board, from vehicles to stationary power plants.