Energy Harvesting from Low-grade Heat Driven Engine to Pump Liquids


Energy - Thermal Power System
Energy - Solar
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The invention is an engine that converts low-grade thermal energy into mechanical work. The innovation in the proposed solution is the possibility of using low-quality heat from renewable energy sources or waste heat in a previously unused manner. A significant advantage of the proposed solution is that this engine does not require electricity for its operation, but only a low-quality heat source (40°C to 170°C), which is commonly available and cheap, and is often a waste product during production processes. In the simplest possible scenario, such a engine can be used as a circulation pump for heat transport systems in solar collectors, apartment heating systems or for extracting water from wells and irrigating farmland.

The laboratory model of the device developed has confirmed the possibility of using the innovative device based on the technology of using two working principles in one workspace, making it possible to create a cheap, simple-to-build and failure-free engine that can be used as a device for pumping water or other liquid medium.


This technology is referred to as isobaric engines. The working principle is illustrated in the following Youtube video -

The technology is based on the use of two working substances in one workspace. Depending on the working medium used, it is possible to obtain high working pressure (up to 300 bar) with low temperature heat source. A low-boiling substance that is responsible for the thermodynamic cycle and a high-boiling substance that is a liquid piston. With the use of two working substances in one working space it is possible to use small amount of low-boiling substance.

The system comprises the following:

  • An evaporator that drives low-boiling substance into vapor
  • A condenser that changes vapor into liquid and make suction
  • A liquid piston for converting pressure to pumping force
  • The valves to separate evaporation and condensing processe
  • Relevant tubes or channels that form the liquid flow paths


This value proposition of the technology is low cost and low on maintenance possibility to convert heat into mechanical power. A simple, cheap and trouble-free design may provide previously unused low-potential heat from solar, geothermal or industrial waste processes and can make it possible to use energy anywhere.

Circulation pump: As a circulation pump for heat transport systems, e.g. in solar collectors, apartment heating systems or for extraction water from wells and irrigation.

Industry application: Enables a wide range of applications in the industrial sector to convert low quality heat into useful work.

Electricity generator: Production of electricity from low-quality heat through a piston or water turbine.


This novel technology offers the following benefits:

  • Affordable: It uses very few elaborate parts, electrical components are minimum (if any). The result is a low cost, low maintenance system.
  • Versatile: It can work with liquids of varying viscosity and temperature.
  • Minimal pump contamination: The pump does not get contaminated by the liquid itself so there is minimal cleaning of the pump head.
  • No electricity: developed device may be running only on heat source and does not require any electricity to work.
  • Scalable: Possibility to make large scale technology.
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