Micro-CHP using steam ejector/water turbine (WaterGen)

d59d32b3-7406-4a85-a686-9767cd4f78cc

Closed

EPSRC
EPSRC
EPSRC
EPSRC
EPSRC

£743,935

Jan. 1, 2016

Dec. 31, 2016

This project will develop an innovative, generic micro-CHP using steam ejector/water turbine (WaterGen), based on an application of existing steam-ejector/water-turbine/wheel technology, which, can bring additional power generation and
carbon reduction solutions over the next decade by the more efficient utilisation of both natural gas and renewable energy. For safety, stability and cost, water is the ideal working fluid. The new technology will address the fundamental UK energy
supply problems.

The project will include a computer program model the theoretical performance of WaterGen. According to the simulations conducted, for entrainment ratios (W steam / W water) 1/2 to 1/9, efficiency (Wnet / Qboiler) is found in the range of 21% to
34%. For the same operating conditions ORC efficiency is found as ~7%. Additional simulations carried out to determine the cycle efficiency for the increasing steam (motive fluid) pressure entering the injector. Entrainment ratio is kept constant
as 1/5 in this analysis. It is found that increasing steam pressure in the range of 1 -5 bar slightly decreases the cycle efficiency from 31% to 30% whilst for the same conditions ORC efficiency varies between 6.5-7.5%. In overall it is found that injector/water cycle has a promising potential to turn low temperature heat (100-150C waste heat /solar energy) into useful power. For the same operating conditions injector/water cycles can provide 4-5 times higher efficiency in comparison with currently used ORC cycles. Moreover, a "proof of concept" rig will be constructed and operated at UoN based on a steam ejector, designed and supplied by Venturi Jet Pumps Ltd (VJP), mated with a commercially available PowerSpout micro-hydroelectric Pelton wheel/generator specified and supplied by Ashwell Biomass Ltd (ABM). The rig will have a nominal electrical output in the range 1 to 1.5 kW. Turbine water flows will be ~ 5 to 25 L/s with heads of 20 to 100 m. The thermal output will be ~ 10 to 15 kW at temperatures in the range 30 to 70C. This scale is small enough for lab operation,
but large enough to obtain meaningful results and to prove the concept. The latter will be fed into the model to assess the performance of larger installations. The consortium is confident that WaterGen can be scaled up, both by adding more units, commonly done in HE schemes, or by using larger turbine/generator/wheel sets for industrial applications.
The steam/water ejector with low cost and easy to manufacture wheel is expected to have good efficiency in converting steam energy into power. The assertion, sometimes made, that steam ejector pumps have low efficiency appears to be in
comparison with electric pumps; but this ignores the losses in generating the electric power to drive the pump so is not a valid comparison. Reasons for anticipating that the overall WaterGen efficiency will be high enough including the following: 1) the lower vapour pressure of water and its good thermal stability means it can operate at higher input temperatures than organic fluids resulting in higher Carnot efficiency. 2) A recent paper indicates experimental steam/water ejector efficiencies can reach 0.85 of the theoretical maximum. 3) Work by Burns suggests that air injection into steam ejector pump improves efficiency. 4) Although the higher the efficiency the better what really matters in a practical unit is the cost/kWh of the power delivered based on its capital and operating costs...WaterGen is anticipated to be a low cost design and higher efficiency than ORC steam expander. The minimum target for the power output is 10% based on the energy input to the boiler. In a developed system efficiencies of 15-20% could be achievable.

Potential Impact:
The impact arising from the project is likely to have significant benefits in the following areas: The UK economy will benefit from the research by increased economy and employment opportunity that may arise from the technology taking up. The market potential for the proposed technology is expected to be substantial as energy savings
and greenhouse gases emissions reduction are set to play an increasing role in the energy sector. This will enable the UK/international companies to develop new businesses. The technology could be internally applied and (or) exported to other countries, such as EU, Asia, Middle East, Africa and China. This may increase UK's economic volume considerably and create new job opportunities, which are expected to be achieved in 5 years commercial development. The significant market potential of the proposed system will provide the UK with economic benefits due to product sales
and employment opportunities. This agreement for exploitation of results will allow the specific technological background of the partners to remain their own property. Only the results of the project will be covered by the agreement and therefore the
agreement will protect the interest of each partner with reference to their technology background.
Being generic, the proposed project has a variety of potential applications for CHP and biomass, waste heat, solar or hybrid sources (e.g., waste heat/natural gas) to power conversion. The early stage funding sought relates to demonstrating "proof of concept" in the lab; consortium experience from previous projects has shown that this credibility is often needed before major industrial companies are willing to become involved in further development. Even at this initial stage an ambitious, but potentially achievable, vision of the business opportunity helps in defining the companies who would be approached to take part in further development, both technical and commercial. The consortium considers that an attractive route to market lies in the manufacturing and operation of self-contained "skid-mounted" sets in the power range 5 to 100 kW.
Although seemingly optimistic, the major components, steam ejector pumps and water turbine/generators, are readily available for this range. In the context of imultaneously reducing carbon emissions and improving the resilience of the Grid, a business model can be developed in which industrial and commercial units are supplied, owned, operated and maintained by companies whose business is providing heating and power utilities as a service, including the interaction with the grid. Essentially such companies become additional providers to the grid with an ability to respond quickly to grid demand through the distributed power networks. This business model facilitates the participation of investment funds, existing power and service companies in addition to equipment manufacturers. Properly constituted would allow the
speedy deployment of a successful generic micro-CHP technology.
The project will benefit the UK in terms of advancing technology, economic opportunities, energy supply security and positive environmental impact, adding value by providing a platform for collaboration between academic and industrial
parties and allowing the UK companies to compete with overseas companies in the field of glasshouses and protected cropping. SMEs will introduce the new technology to the market with the direct creation of new jobs and further employment throughout the supply chain in the energy sector. Manufacturing industries will benefit from the sales of a new product offered both in the UK and overseas.