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Faculty of Mechanical Engineering

Development of a natural gas expansion machine to produce electricity under using geothermal energy without additional heating

Project description

Conception and experimental testing of prototyp system (Expander, Generator, Regulation)

The potential pressure difference between natural gas transport systems and the distribution systems offers an opportunity for electricity generation. This can be realised for example by  expansion machines. During this expansion process the temperature decrease due to Joule-Thomson-Effect, therefore it is necessary to preheat the natural gas to prevent condensate formation and freezing in pipelines. The preheating of natural gas is realised solely with geothermal energy and thus without additional heating equipment. In a preliminary study it can be shown that a useful power of 14-18 kW can be generated with a mass flow rate of 1 kg/s and by a temperature decrease of 10 °C. Aim of the project is to develop a most efficient and most economical concept to realise a prototype system.

hs diagram for natural gas to visualise the enthalpy potential without preheating
Internal power as a function of inlet pressure for an isentropic efficiency of 1 and 0.5

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Cooperation / Funding

This project has been carried out as part of an industrial cooperation.