(H)olistic (A)pproach to the Design of Efficient Heat (R)ecovery Systems for Electrical (P)ower (P)roduction (HARP^2)

Lead Research Organisation: University of Manchester
Department Name: Electrical and Electronic Engineering


HARP2 is a £1.2M consortium that brings together the Universities of Manchester and Huddersfield, as well as a range of industrial project partners, to achieve a technological step-change in the design and application of environmentally-friendly, high-efficiency and fully-integrated waste heat recovery systems for generation of electrical power. This demonstration project will cover three main areas: (i) novel topologies of thermoacoustic engines, coupled with (ii) reciprocating electrical machines using innovative drive/control techniques, and (iii) novel manufacturing technologies to fabricate complex multi-scale objects into compact and robust pressure systems. These have to be optimised for future low-cost and mass-production, and to fit a wide range of potential technological applications, including internal combustion engines for land and marine transportation, micro-CHP (combined heat and power) systems in domestic or small commercial gas/biomass fuelled boilers, railway rolling stock, or industrial process units, to name just a few.

To achieve this end, a challenging multi-disciplinary work programme has been developed requiring a close collaboration between research institutions. This must cover aspects of: modelling and experimental validation of thermoacoustic systems, in particular travelling-wave cascade engines optimised for maximum thermal efficiency, building and validating acoustic impedance coupling models between thermoacoustic systems and linear alternators (LAs), developing inexpensive alternator designs and appropriate control strategies for maximum power-point tracking using adaptive acoustic impedance matching, structural analysis for high pressure and fatigue loading, and suitable fabrication protocols in the manufacturing context to ensure the successful integration and packaging of all sub-systems into a working proof-of-concept demonstrator.

Six industrial companies, familiar with R&D and product development processes on the academia-industry interface, are supporting the project through their participation in the steering committee - denoted the Industrial Advisory Board (IAB) in the HARP2 programme - and through in-kind contributions of staff time and facilities to provide application-oriented guidance to the project. The companies include British Petroleum Plc, Spirax Sarco Ltd, Ricardo UK Ltd, Ashwell Biomass Ltd, European Thermodynamics Ltd and Reliance Precision Ltd, and are represented in the IAB by their technical leads. The companies cover relevant technical areas, in particular process industries, transport (road/rail/marine) and boiler manufacturers as well as the manufacturing sector. The intention is to grow the membership of the IAB through a mix of public engagement and dissemination activities targeted at industry and policy-makers.

This complex research programme aligns directly with the EPSRC "themes" of Energy (improvement in the UK's energy balance by a wider utilisation of waste heat from multiple sources and novel solutions for future renewable technologies), Manufacturing the Future (by devising novel and competitive products and processes and new materials concepts with bespoke properties), and, in an extended way, Global Uncertainties and Living with Environmental Change (by reducing environmental impacts of energy utilisation activities).

In particular, it aims to make significant contributions to the future of the UK's energy sector such as (i) unlocking the potential of co-generation and (ii) reduction in CO2 emissions. It is estimated that the technical capacity for cogeneration in the UK will be 40 GWe by 2030, while the technically recoverable heat from industrial processes amounts to 11 TWh/y, corresponding to 2.2 million tonne of CO2 being abated. The HARP2 TAG technology may provide significant contributions to achieving these two goals which makes the research extremely timely.

Planned Impact

The planned research will generate impacts in the four key areas identified by the EPSRC: "Knowledge", "People", "Economy" and "Society", as summarised below:

KNOWLEDGE: The detailed analysis of the research disciplines affected by this research is given under the "Academic beneficiaries" heading. It is important to emphasize that the project brings together researchers from traditionally compartmentalized disciplines such as electrical/electronic engineering, thermal & fluid sciences and manufacturing in a bid to integrate the underlying fundamental, modelling and applied knowledge to devise a complex system that could be a potential game-changer in successful waste heat recovery. It is this particular methodology of a holistic design that will be of paramount importance to both the academic and industrial R&D community, especially those working in optimisation of energy management processes.

PEOPLE: The immediate impact will be on the university staff involved: 3 PDRAs, 6 academics, 3 technical/EO members. All will need to gain new knowledge, inevitably encountering "uncharted" territories in their own specialisms, and learning to communicate their knowledge across discipline boundaries. Very likely, the project will generate related research questions for associated PhD programmes thus resulting in additional training routes. In the longer term (e.g. 3-5 years), after the "holistic" design approaches have matured, the universities will integrate the methodologies into their MSc and CPD courses. In parallel, training of the staff of the industrial project partners (especially in R&D departments) will take place through respective two-way placements. A wider impact on industrialists will be achieved through both the proposed HARP2 dissemination workshop and publications in professional journals. All these arrangements are intended as "People Pipeline".

ECONOMY: The key to a successful impact is the early involvement of the industrial partners through the steering committee (IAB) in order to focus the efforts on the end users' needs. The IAB will also act as HARP2 TAG technology "ambassadors" in industry. Meanwhile, the project will develop substantial IPR invested in university spinouts (3-5 year horizon), who will develop licensing arrangements with fabricators serving the end-user companies (generation of new companies, products and procedures in 5-10 year horizon). This will clearly lead to wealth and jobs creation and future inward investment to develop improved products within the "green economy" theme. The project will also impact the economy in indirect ways, for instance by reducing the need for dealing with environmental impacts created by current inefficient processes. It is envisaged that such impacts will be long-lasting, well into 10-20 year horizon.

SOCIETY: The societal impacts will include: (1) Educating the general public on environmental pollution and sustainability matters and ways to address these, in particular the use of TAGs for waste heat recovery and additive manufacturing in engineering the UK's cleaner, greener and more sustainable energy future. (2) Implementation of new policies in areas such as waste heat recovery, use of CHP systems, co-generation of electricity saleable to the grid or additional electricity for rail traction. A successful project demonstration will make a significant contribution to the resolution of the energy trilemma (energy security, affordability and zero/low carbon emissions). In the long term (e.g. 10-20 years) the technological developments will impact the nation's quality of life. This will be through creation of jobs and the provision of cheaper products and services (re-using waste heat simply saves pounds). Similarly, cleaner environment achieved through lowering the harmful emissions from fossil fuels through recycling of waste heat will inevitably lead to improving the nation's health and longevity.
Description As part of the work-package on control, a novel control technique for resonance tracking and maximum power point tracking has been developed and validated experimentally.
The control technique is able to adjust the operating parameters of the linear electric generator automatically so as to maximise the power converted from pressure waves into electric and cope with system's uncertainties and changes in the operating conditions of the prime energy source. This is of paramount importance for practical applications, in order to build efficient, compact and cost-effective thermo-acoustic generators.
The proposed technique is not limited to thermo-acoustic generators but is applicable to a variety of energy harvesting applications (such as vibrations, waves etc.).
The proposed resonance-tracking framework is allows continuous resonance monitoring and is relevant to systems where resonance must be prevented to avoid catastrophic failure.
The research activity within this work-package has also produced a theoretical approach to for the analysis and synthesis of control systems based on perturb & observe strategy operating in oscillating systems.
Exploitation Route Liaising with companies and researchers operating in the wave energy (e.g. small power take-off devices) and energy harvesting sector may provide a possible path to bring these results to fruition within a broader community. This may be achieved through outreach events such as conferences and seminars. Also, approaching relevant industrial companies directly, will offer a path to further developments in order to move the control technology to higher TRL and implement it into products. For instance, there is a growing demand for energy-harvesting systems to feed condition monitoring apparatus (e.g. for critical infrastructure) and surveillance systems, where the developed control approach would be highly relevant. Finally, the developed theoretical framework may be incorporated into course units (e.g. Design of Electric Drives, Interfacing Clean Energy Systems, Advanced Control) within MSc programmes at the host academic institution to train a new generation of engineers on energy harvesting technologies.
Sectors Energy,Environment

Description The impact on knowledge has been mainly on the relevant areas of control engineering and electric motors & drives / electromagnetics, and has been enabled via publication on discipline-specific high-ranking journals as discussed in the key findings / outcomes section. The grant has also contributed to the professional development of two post-doctoral research associates (one now working with a UK R&D private centre, the other one being currently a PDRA in another project on Wave Energy Systems), and one PhD student. Since the autumn of 2019, some light-touch aspects of resonance tracking and MPPT concepts developed in the research programme have been incorporated in some UG and MSc courses thought at UoM (Mechatronics, Interfacing Clean Energy Systems). The project started in mid-2018 and run through 2019 as planned, but it was then affected by Covid 19 pandemic when it was entering its critical path in early 2020. In particular, the lockdown in 2020, and early 2021 has caused severe delay on the experimental activities of model validation. These were instrumental to assembling an operational demonstrator, which had then to be put on hold. Equally, the planned Workshop as a key part of the dissemination strategy could not take place. There are however plans to seek for some industrial funding in order to resume and finalise some of the pending activities regarding the demonstrator as part of two PhDs (self-funded).
First Year Of Impact 2020
Sector Education
Impact Types Societal

Title Resonance tracking algorithm 
Description The algorithm is able to track and enforce resonance conditions in reciprocating permanent-magnet linear generators driven by pressure waves. The algorithm is suitable for real-time implementation. 
Type Of Material Computer model/algorithm 
Year Produced 2020 
Provided To Others? Yes  
Impact The algorithm is suitable for real-time implementation and has been considered for maximising power conversion in other energy-harvesting applications apart from thermoacoustic devices (e.g. piezo-electric actuators for energy harvesting from vibrations). Two IEEE journal papers have stemmed out from the proposed resonance tracking algorithm. 
Title emulation of wave sources with output impedance 
Description Development of a programmable electromechanical emulator able to represent a "pressure wave source" with varying characteristics and to couple with / drive a linear alternator in order to test linear alternator drives and related control approaches for TAE applications and beyond (e.g. energy harvesting from vibrations, wave energy) 
Type Of Material Computer model/algorithm 
Year Produced 2021 
Provided To Others? Yes  
Impact One IEEE journal paper has been published on the proposed emulation technique.