A consistent methodology incorporating usefulness of the regenerator and heat exchanger for alternative forms of Brayton & Inverse Brayton cycle compared to the basic Brayton and regenerative Brayton cycles has been presented. An analytical study has been performed to explain why regenerator and heat exchanger might be useless at particular operational conditions. This analysis showed that regenerator and/or heat exchanger of the Brayton & Inverse Brayton cycle should be removed from the service at particular pressure ratio operations. Thermal performances of all unit arrangement were accordingly calculated at the moderate range of compressors' pressure ratios. Analytical and computational findings showed that a particular unit arrangement including a regenerator between the two stages of expansion processes through turbines exhausting to the atmospheric pressure had a better thermal performance, i.e. at least 14% greater than all other unit arrangements, while the huge heat exchanger and second compressor could be eliminated for lower occupation space and start up process. (C) 2016 Elsevier Ltd. All rights reserved.