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Thermogravitational Cycles: Theoretical Framework and Example of an Electric Thermogravitational Generator Based on Balloon Inflation/Deflation

Ford, IJ; Nightingale, C; Elson, T; Sandre, O; Aouane, K; (2018) Thermogravitational Cycles: Theoretical Framework and Example of an Electric Thermogravitational Generator Based on Balloon Inflation/Deflation. Inventions , 3 (4) , Article 79. 10.3390/inventions3040079. Green open access

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Abstract

Several studies have involved a combination of heat and gravitational energy exchanges to create novel heat engines. A common theoretical framework is developed here to describe thermogravitational cycles which have the same efficiencies as the Carnot, Rankine, or Brayton cycles. Considering a working fluid enclosed in a balloon inside a column filled with a transporting fluid, a cycle is composed of four steps. Starting from the top of the column, the balloon goes down by gravity, receives heat from a hot source at the bottom, then rises and delivers heat to a cold source at the top. Unlike classic power cycles which need external work to operate the compressor, thermogravitational cycles can operate as a “pure power cycle” where no external work is needed to drive the cycle. To illustrate this concept, the prototype of a thermogravitational electrical generator is presented. It uses a hot source of average temperature near 57 °C and relies on the gravitational energy exchanges of an organic fluorinated fluid inside a balloon attached to a magnetic marble to produce an electromotive force of 50 mV peak to peak by the use of a linear alternator. This heat engine is well suited to be operated using renewable energy sources such as geothermal gradients or focused sunlight.

Type: Article
Title: Thermogravitational Cycles: Theoretical Framework and Example of an Electric Thermogravitational Generator Based on Balloon Inflation/Deflation
Open access status: An open access version is available from UCL Discovery
DOI: 10.3390/inventions3040079
Publisher version: https://doi.org/10.3390/inventions3040079
Language: English
Additional information: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Keywords: Thermogravitational cycle; thermogravitational electric generator; pure power cycle; Carnot; Rankine; and Brayton cycles; gravitational force; compression and expansion; waste heat; geothermal or solar energy harvesting
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/10065398
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