An integrated smart thermo-chemical energy network

Managing the intermittency of renewable sources together with transient (hourly to daily to seasonal) energy demands is one of the principal challenges of delivering a net-zero energy system. Smart multifunctional thermo-chemical energy networks represent an alternative energy network and storage system, a solution based on the distribution of energy via thermo-chemical material rather than thermal energy, gas, fuels or electricity– an option that has scope for integrated short- and long-term energy storage. This is the first research work to realise such a system and demonstrate how it might operate using smart control strategies and how thermo-chemical fluids (TCFs) can be used as a medium for timely energy storage and distribution. The experimental study also describes the effect of steady and variable heat sources on TCF regeneration performance and estimates the potential of thermo-chemical energy networks, which would be particularly beneficial in buildings with high energy consumption for humidity control. This research proves the practicality of the design idea for such a network, which would be governed by centralised control, regenerated by steady or transient heat loads and capable of supplying a variety of demands in an experimental setting. The energy and economic potential of the network were also assessed, identifying temperature and humidity control application scenarios with energy savings of more than 60% compared to conventional operation and payback periods of 6.6–9.7 years

The real-time interaction model for transient mode investigations of a dual-piston free-piston engine generator

A free-piston engine generator is being developed worldwide as a novel means of electrical power generator for light vehicle application, which can provide a complementary solution towards reducing carbon dioxide emissions of road vehicles in general. However, the absence of a crank-slider mechanism in free-piston engines resulted in poor transient operations. Transient real-time modelling and simulation can provide the interaction between in-cylinder combustion with dynamics of piston motion, which has not been fully explored previously. This paper presents a real-time interaction model between dynamics of the piston motion and thermodynamics of the in-cylinder combustion of a two-stroke spark ignition dual-piston free-piston engine generator for transient operation investigations. The simulation model was developed based on the working prototype and comprised of zero- and one-dimensional sub-models interacted in real-time governed by a single timestep. The study focuses on three critical transient modes: motoring, starting and generating for the transient performance investigation. A series of experimental results during motoring was used for validating the simulation model, which showed good agreement between simulation and experiment results with 2–5% errors. The targeted brake thermal efficiency is around 20–30% at 50–60 Hz engine speed which has been shown achievable. Transient speeds of 10 and 25 Hz produced higher combustion pressure around the top dead centre but suffered pumping loss at the end of the expansion stroke. The lower peak pressures at 50 and 60 Hz have contributed to the lower brake mean effective pressure values. Maximum brake thermal efficiency of 25.8% lies in the mid-range of compression ratios between 10:1 to 15:1 while at the cyclic speeds of 50 Hz to 60 Hz. Maximum brake mean effective pressure contour occurs between 5 and 12.5 compression ratios and corresponding speeds of 10 to 30 Hz. It was observed that the excess energy from combustion results in piston overshoot condition while insufficient energy prevents the piston from achieving the targeted stroke and compression ratio. Knock events were observed for high compression ratio cases regardless of engine speed. Predictive stroke control and knock detection capability are the main contribution of the real-time interaction model presented in this paper for realistic transient operation investigation and performance prediction of the dual-piston free-piston engine generator

Comparative analysis on temperature swing adsorption cycle for carbon capture by using internal heat/mass recovery

Due to relatively high energy consumption of absorption technology, adsorption carbon dioxide capture is gathering the momentum in recent years. This paper aims to further improve the thermal performance of a 4-step temperature swing adsorption cycle by integrating internal mass recovery and heat recovery. Exergy efficiency is evaluated by using adsorption characteristics of activated carbon and compared in terms of four different situations i.e. basic cycle, heat recovery cycle, mass recovery cycle, heat and mass recovery cycle, which could illustrate the advantages and disadvantages of different recovery technologies. Results demonstrate that heat recovery and mass recovery technologies are quite conducive to improve the up limit of cycle thermal efficiency. Under the conditions of different desorption/adsorption temperatures and pressures, exergy efficiencies using recovery technologies could be improved by up to 2.86 times when compared with that of basic cycle. Besides, in real application unused percentage of adsorption reactor and metal ratio have large influence on the cycle performance while mass recovery rate has a relatively small influence. One potential application of the proposed recovery technologies is direct air capture in building ventilation system since a largest improvement could be achieved at a low carbon dioxide concentration

Design and parametric analysis of Linear Joule-cycle Engine with out-of-cylinder combustion

AbstractFor all the existing prime movers including internal combustion engine and gas turbine, there is an inherent problem as the efficiency penalty in their micro scale applications. Crankshaft mechanism in internal combustion engine causes nearly half of the friction loss originating in piston-ring-cylinder contacts. Rotomachinery of compressor and turbine results in low compression and expansion efficiencies when gas turbine downsizes to couple kilowatts. Linear Joule-cycle Engine (LJE) is designed to hire Joule cycle and out-of-cylinder combustion, to configure a double-acting free piston setup without crankshaft mechanism. The paper introduces the innovative design of LJE and optimises its geometry parameters in LMS Imagine.Lab AMESim. The parametric analysis provides a solid basis to prototype manufacturing. The potential of the technology lies on micro energy supplies using various renewables

Special issue: Sustainable thermal energy management in the process industries conference (SusTEM2010)

SusTEM2010 was organised by the Process Industries Thermal Energy Management (PRO-TEM) Network and held on 2nd–3rd November 2010 in the Great North Museum, Newcastle upon Tyne, UK. PRO-TEM is a research network, funded by the Research Councils UK Energy Programme, whose aim is to promote and disseminate internationally recognised research and support knowledge transfer to all stakeholders associated with the process industries. Newcastle Science City and Newcastle Institute for Research on Sustainability provided additional financial support to make this conference possible.SusTEM2010, which attracted a large number of delegates from academia, industry and non-governmental organisations, was delivered in parallel sessions covering barriers and challenges, heat exchangers, industrial applications, process modelling and thermal power. All are important themes in the quest to improve thermal energy management and the research presented is applicable to a number of sectors and processes used in the industry. The best papers presented at the conference are included in this special issue

The control of a free-piston engine generator. Part 1: Fundamental analyses

Free-piston engines are under investigation by a number of research groups due to potential fuel efficiency and exhaust emissions advantages over conventional technology. The main challenge with such engines is the control of the piston motion, and this has not yet been fully resolved for all types of free-piston engines. This paper discusses the basic features of a single piston free-piston engine generator under development at Newcastle University and investigates engine control issues using a full-cycle simulation model. Control variables and disturbances are identified, and a control strategy is proposed. It is found that the control of the free-piston engine is a challenge, but that the proposed control strategy is feasible. Engine speed control does, however, represent a challenge in the current design.Free-piston Linear engine Dynamics Control

Investigating a conventional and retrofit power plant on-board a Roll-on/Roll-off cargo ship from a sustainability perspective – A life cycle assessment case study

AbstractFollowing the enforcement of MARPOL Annex VI Regulations for the Prevention of Air Pollution from Ships, retrofitting conventional power plants with emerging technologies is seen as a means to promote sustainability of marine transport and comply with more stringent emissions legislation. However, a knowledge gap exists as the environmental performance of retrofit power plant solutions incorporating emerging technologies has not been examined using an integrated system approach based on Life Cycle Assessment. The purpose of this research was to investigate if integrating selected emerging technologies i.e. photovoltaic systems, lithium-ion batteries, cold ironing and power-take-off/power-take-in systems supplemented by frequency converters and variable frequency drives into an existing power plant would be to the advantage of a chosen ship type i.e. Roll-on/Roll-off cargo ships, from the perspectives of resource consumption and environmental burden. Using the power plant of an existing vessel as a case study, it was found that cast iron, steel, copper and aluminium were the four materials most commonly consumed during manufacturing phase i.e. 2.9×105kg, 1.9×105kg, 5.3×104kg and 2.9×104kg respectively. By burning 2.9×107kg of heavy fuel oil and 2.3×108kg of marine diesel oil during operation, 8.2×108kg of carbon dioxide, 1.7×107kg of nitrogen oxides, 6.1×106kg of sulphur dioxide, 7.6×105kg of carbon monoxide, 6.5×105kg of hydrocarbon and 4.7×105kg of particulate matter would be released. Over a projected 30-year period, emissions released to air and freshwater were found to be significant. Based on 3 characterisation methodologies, ecotoxicity potential, with 7–10 orders of magnitude, was identified as the most significant environmental burden. Consuming and storing resources had the least impact, operating diesel engines and auxiliary generators had a moderate impact, and disposing metallic waste had the highest impact. The research concluded that the environmental burden caused by a marine power plant was significant but retrofitting existing power plant with suitable emerging technologies could reduce a number of impacts by 4–7 orders of magnitude, as verified via scenario analysis. However, the system should be designed and managed with due care as the environmental benefits, such as lower fuel consumption, emission reduction and performance improvement in some environmental measures are always achieved at the expense of an increase in other detrimental impacts

Coupled dynamic-multidimensional modelling of free-piston engine combustion

Free-piston engines are under investigation by a number of research groups worldwide, as an alternative to conventional technology in applications such as electric and hydraulic power generation. The piston dynamics of the free-piston engine differ significantly from those of conventional engines, and this may influence in-cylinder gas motion, combustion and emissions formation. Due to the complex interaction between mechanics and thermodynamics, the modelling of free-piston engines is not straight-forward. This paper presents a novel approach to the modelling of free-piston engines through the introduction of solution-dependent mesh motion in an engine CFD code. The particular features of free-piston engines are discussed, and the model for engine dynamics implemented in the CFD code is described. Finally, the coupled solver is demonstrated through the modelling of a spark ignited free-piston engine generator.Free-piston engine Dynamic modelling CFD

The control of a free-piston engine generator. Part 2: Engine dynamics and piston motion control

Free-piston engines are under investigation by a number of research groups due to potential fuel efficiency and exhaust emissions advantages over conventional technology. The main challenge with such engines is the control of the piston motion, and this has not yet been fully resolved for all types of free-piston engines. This paper builds on the fundamental investigations presented in the accompanying paper and investigates the dynamics of the engine and the feasibility of classical control approaches. The response of the engine to rapid load changes are investigated using decentralised PID, PDF and disturbance feedforward. It is found that the engine is sensitive to rapid load changes but that in constant power applications standard control techniques provide satisfactory performance. The influence of cycle-to-cycle variations in the combustion process are investigated, but not found to be critical for engine operation.Free-piston Linear engine Dynamics Control

A Detailed Optimisation of Solar Photovoltaic/Thermal Systems and its Application

There have been various studies and experimental results analysing the operational behaviour of PVT, most of which has been done at steady state or quasi-state. Variable factors can be controlled to optimise the PVT output such as mass flow rate, irradiation falling on the PVT through tracking or incidence angles in a day and fixed factors that depend on the design of the chosen PVT system as well as location parameters such as ambient temperature, wind speed, Transport Fluid used, Difference in Structure, Packing Density, Nominal operating temperature, stagnation temperatures, Fill Factor, Thickness of each layer, Location and Latitude and Heat removal factor (harp or serpentine design). The aim of this research is to validate and predict the dynamic behaviour of PVT systems while accurately describing the factor responsible for the loss of efficiency at any point in time under various weather constraints. A commercial system was considered (Solar Angel PVT system) here and is simulated for an entire year. The system was modelled in MATLAB and solved in implicit RK-4 method. The research question finds out to establish the basis for a standard testing protocol for assessing PV-T performance throughout various differences. It also analyses the long-term dynamic performance of PV/T technology by providing evidential data analysis (solar irradiance, heat and electricity, ambient temperature, operational temperatures, flow rates and thermal storage capacity) while completing an assessment of PVT behaviour with respect to an equivalent PV under different weather conditions. The flow rates, heat removal factor and the location affect the thermal behaviour of the PV/T to a greater extent than nominal temperatures and stagnation temperatures