Power Generation and Heat Recovery from Industrial Waste Heat with Advanced CO2 Thermodynamic Power Cycles (CO2Power)

Lead Research Organisation: Brunel University
Department Name: Mech. Engineering, Aerospace & Civil Eng


he vast volumes of waste heat rejected from industrial processes can be converted into electricity and useful heat through advanced energy conversation technologies. In this project, a test rig of a small-scale power generation (up to 5kW) and heat recovery system will be established with a heat source temperature between 100 ^C and 500 ^C, which is representative of actual industrial waste heat. The natural refrigerant CO2 will be engaged as a working fluid in the system, considering its excellent thermophysical properties and negligible environmental impact. Corresponding to the large temperature range of the heat source, the CO2 supercritical Rankine cycle will be applied for temperatures below 350 ^C, otherwise, combined CO2 Brayton and supercritical Rankine cycles will be employed. Simultaneously, a detailed mathematical model for the proposed system will be developed and validated with measurements. The model will then evaluate, compare and analyse different system and component designs, heat recovery potentials and control optimisations which will eventually lead to optimal design and construction of the proposed system.

Planned Impact

In the UK and even whole worldwide, currently around 70% of the electricity consumed is generated by burning fossil fuels in central power stations. The extensive consumption of fossil fuels has caused significant atmospheric pollution, global warming and rising energy costs. One of the critical challenges of the 21st century for the UK government is to cooperate with all other countries in the world to tackle these risks surrounding excessive CO2 emissions by replacing fossil fuels with waste heat and renewable energy sources for the power generation. This is essential to meet the government's target to reduce the UK CO2 emissions by 80% of 1990 levels by 2050. It is therefore imperative to continue improving the capability and competiveness of manufacturing industry particularly in the energy sector. With increasing electricity demand year on year, CO2 emissions will increase if power generation cannot be decarbonised. The development of high efficiency low and medium temperature electricity generation systems with advanced CO2 combined Brayton and supercritical Rankine power cycles can make substantial contributions to the national and international efforts of saving energy resources and CO2 emissions.

The manufacturing capability in the UK energy sector is relatively weak, particularly in power generation with low and medium temperature energy resources from industrial waste heat and CO2 combined Brayton and supercritical power cycles. There are currently a range of low temperature nonCO2 ORC products in the market, but they are mostly designed and manufactured from outside of the UK. The research programme proposed here will build on the fundamental understanding of the low and medium temperature energy conversation system for industrial waste heat with the CO2 combined power cycles and their design and control optimisation to provide maximum efficiency over a wide range of conditions. The project will increase the technical knowledge and CO2 supercritical power generation system manufacturing capability in the UK. This should enhance their share of the expanding local and export markets for CO2 power components and systems. It will also provide training and employment opportunities in the UK energy and manufacture sectors

The UK research community is underrepresented in the international effort to develop efficient CO2-based low and medium temperature power generation systems and equipment. The applicants in this proposal are leading the research in the UK on CO2 refrigeration systems , thermodynamic cycle analyses and heat exchangers and the outcomes from this project pave the way for wider engagement of the academic community in the research on CO2 supercritical power systems. The research will provide insights into the design and optimisation requirements of the CO2 gas heaters and expanders at different flow and heat transfer regimes. The models, operational data, and fundamental knowledge developed will inform the work of other researchers, and this should accelerate the design, control optimisation and deployment of efficient CO2 supercritical power systems to the market and contribute to significant reductions in CO2 emissions to the environment.

Project outputs will be widely disseminated by Brunel University and the industrial partners to raise awareness the development, technology, design and manufacture of the new system. Seminars and presentations will be given at the university and meetings of professional and trade organisations such as the Institute of Energy. Publicity material will be fed through to large energy sectors to raise awareness of the new product offerings. The research will also be communicated through papers in high-impact, peer reviewed journals and presentations at a wide variety of conferences.
Title A brief video introduction for the research project 
Description A brief video introduction for the research project was made. This includeed the test rig explanation , research outcomes and further development in this area. 
Type Of Art Film/Video/Animation 
Year Produced 2015 
Impact The video has demonstrated clearly the development , operation and application of the project. This will facilitate potential future collaboration and development in this area. 
Description 1) A multi-functional and high precision test rig for the CO2 power generation system with low temperature heat source and CO2 transcritical power cycles has been designed and built up.

2) The complex energy conversion processes involved in the CO2 power system have been investigated experimentally and the system performance data has been obtained through the use of advanced measurement technologies.

3) Detailed transient simulation models for the CO2 power system and components have been developed and validated with experimental results.

4) The heat transfer and thermal behaviour of major components, particularly CO2 gas heaters, condenser and expander in the CO2 power system, and system thermal and exergy efficiencies have been investigated through experiment and simulation modelling.

5) The strategies to control the CO2 power generation system and design optimally the system , components and CO2 power cycles have been attained.
Exploitation Route 1) Further performance improvements of the main system components are necessary including CO2 turbine, CO2 liquid pump and CO2 air cooled condenser;

2) The system can be more efficient, reliable and compact if the liquid pump and air cooled condenser could be replaced with compressor and water-cooled condenser respectively;

3) Control strategies need to be further improved in terms of liquid pump speeds and turbine rotation speed.

4) the system model needs to be further developed to integrate detailed control strategies.
Sectors Agriculture, Food and Drink,Education,Energy,Environment,Manufacturing, including Industrial Biotechology,Retail,Transport

Description From our research outcomes from this project we have found that the efficiency of CO2 turbine needs to be further improved and we have identified where to improve the turbine efficiency.
First Year Of Impact 2015
Sector Creative Economy,Education,Energy,Environment,Government, Democracy and Justice,Manufacturing, including Industrial Biotechology
Impact Types Economic

Title Mathematical model of power generation system with CO2 transcritical power cycles 
Description A model of power generation system with CO2 transcritical power cycles has been developed and validated with the corresponding test results. The system model is an integration of a number of system component models including CO2 turbine, recuperator, air cooled condenser, liquid pump , gas generator and controls. The model can be used to evaluate and optimize the design and performance of the system and components and will be able to achieve system scale-up for actual installation. 
Type Of Material Computer model/algorithm 
Year Produced 2015 
Provided To Others? Yes  
Impact The developed and validated models of the CO2 power generation system and components can be used as an efficiency tools for the system performance evaluation , optimization and potential system scale-up for actual installations. The model simulation can generate more prediction results and data at extensive operating states which will be very helpful to understand the system operations , controls and component heat transfer processes. 
Title Design software for power generation with biomass combution and CO2 transcritical/supercritical power cycles 
Description Based on the developed and validated models of the tested power generation system with biomass combution and CO2 transcritical/supercritical cycles, a design software of the corresponding system and components has been developed. 
Type Of Technology Software 
Year Produced 2018 
Impact The software will facilitate the system performance evaluation and optimization and potential system scale up for actual installation and operation. 
Description FLEXIS Young Researchers Conference 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact The conference of 'FLEXIS Young Researchers Conference' was held at Cardiff on Friday 13th July 2016.
The conference is designed to:
i) Bring together academic and industry leaders with interest in waste heat recovery and its efficient utilisation
ii) Share knowledge of both products and applications
iii) Learn of recent and emerging technology developments

More than 100 people mostly from both academics and Industries in the UK attended this event. Potential collaborations between University f South Wales and industries and other institutions are expected in the area of waste heat recovery.
Year(s) Of Engagement Activity 2018