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The ongoing energy transition is driven by a need to mitigate climate change and switch from fossil to low-carbon fuels and renewable energy. However, while technologies such as onshore and offshore wind energy, solar energy, and batteries have made significant progress over the past decades, and they can increasingly compete directly with fossil fuels, their deployment is still only a fraction of what is needed to fully decarbonize our economy-a process that is going to take at least several more decades and is going to require major investments. Also, the intermittent character of especially wind and solar energy will require major changes in, for example, storage of energy (both heat and electricity). How this transition will play out, and which technologies will ultimately become winners and losers are highly relevant questions which this book will help to answer by providing both the individual market deployment and cost reduction trends per technology and the results of modeling a portfolio of energy technologies in various sector models and overall energy models.

A novel dual source vapor injection heat pump (DSVIHP) using exhaust and ambient air is proposed. The air exhausted from the building first releases energy to the medium-pressure evaporator and is then mixed with the ambient air to heat the low-pressure evaporator. A vapor injection (VI) compressor of two inlets is connected with the low and medium pressure evaporators. It's first time that a VI compressor is employed to recover the ventilation heat. The system can minimize the ventilation heat loss and provide a unique defrosting approach by using the exhaust waste heat. Fundamentals of the proposed DSVIHP are illustrated. Mathematical models are built. Both energetic and exergetic analyses are carried out under variable conditions. The results indicate that the DSVIHP has superior thermodynamic performance. The superiority is more appreciable at a lower ambient temperature. It has a higher COP than the conventional vapor injection heat pump and air source heat pump by 11.3% and 23.2% respectively at an ambient temperature of -10 °C and condensation temperature of 45 °C. The waste heat recovery ratio from the exhaust air is more than 100%. The novel DSVIHP has great potential in the cold climate area application.

This paper investigates a novel micro-channel flat separated loop heat pipe system for cooling the information technology equipment in the data centres through theoretical and experimental analysis and by assessing the impact of the inlet water temperature on system performance. A computer model is developed to simulate the steady-state performance of the micro-channel flat separated loop heat pipe system. After comparing the experimental and modelling results, the new and conventional system under the same working conditions, the model is validated yielding high accuracy in predicting the performance of the micro-channel flat separated loop heat pipe system with recorded error being limited to 2.16–8.97%. The new system has better performance than the conventional system. Under the operating conditions of heat load intensity of 1,000 W/m2, water flow rate of 0.28 m3/h, refrigerant filling rate of 30%, ambient air temperature of 26°C, and evaporator and condenser height difference of 0.8 m, the performance of the system has been explored at inlet temperature from 15 to 24°C with increments of 3°C. The system’s averaged heat transfer efficiency was found to decrease with the increase in inlet temperature. This research provides valuable insight into the data centre information technology equipment cooling, which is of great significance for energy saving and environmentally friendly operation of data centres.

In this paper, a novel photovoltaic/thermal system using micro-channel flat loop heat pipe (PV/T-MCFLHP) is proposed, and the thermal and electrical performance of the system is investigated theoretically and experimentally. The variations of temperatures were analysed, and the efficiency of the system was calculated under different conditions, i.e. simulated solar radiation, water flow rate and refrigerant filling ratio. The maximum overall efficiency of the system was found to be 51.3%, the thermal efficiency 43.8% and the electrical efficiency 7.5% with the refrigerant filling ratio of 25%, simulated solar radiation of 800 W/m2 and water flow rate of 400 L/h. Test results were compared with simulation results, and the recorded average error was 10.2%.

In order for a solar heating system to provide heat immediately after sunrise, a fast response is needed to the heat demand of a serviced space. The majority of existing solar heating systems have a slow response time due to the large volume of water stored in the heat storage/exchanger unit (HSEU). This leads to a slow heat delivery cycle, which results in discomfort for the occupants and thus creates a huge barrier to the wide deployment of solar heating systems. To overcome this critical issue, a novel interactive heat storage/exchanging unit (HSEU) employing a double-tank configuration was developed. Unlike conventional HSEUs, which have a single tank acting as the heat storage and exchanging unit, the new HSEU is comprised of a small tank for heat exchange combined with a large tank for heat storage. The small tank enables fast transfer of solar heat to the heating loop fluid without having to heat up the large volume of water in the entire HSEU tank, whilst the large tank is used to store and exchange heat between itself and the small tank using a temperature-oriented control mechanism. To test the proposed design, the heat transfer between the first (solar loop) and second (heating loop) fluids, the heat and mass transfer between the small and large tank and the associated operational strategy were investigated experimentally and theoretically for comparison. A conventional single tank HSEU requires around 120 min to deliver heat to a served space, whilst the new interactive double-tank HSEU can provide heat to the served space in around 20 min, thus creating a heating system which can respond significantly faster than traditional systems. The investigation of the heat exchange effect between the solar and heating loop fluids showed that the new HSEU achieved a convective heat transfer coefficient of as high as 391 W/m2·K, which is 551% higher than that of a conventional tank. As a result, the solar thermal efficiency of the solar panel-array in the new HSEU

This paper presents a comprehensive review on developments and advances of Solar Assisted Heat Pump technology reported in 21st century. Combination of thermal and photovoltaic solar collectors with heat pumps has been widely used in recent decades for simultaneous heat, hot water and power generation for a broad range of applications, from providing domestic and commercial buildings with heat and power to manufacturing and agricultural applications. This review critically analyses the research reported in past two decades with particular attention to the works with substantial importance for future development of the technology. Four distinctive investigation periods were considered and key developments and dominant technologies at each period were reported. The main novelties and breakthroughs in solar assisted heat pump technology, as identified by this review, are: (1) The ban on R-12 refrigerant which lead to dominance of R-134A refrigerant for a wide range of systems and applications, (2) Increasing interest in Solar-assisted Ground Source Heat Pumps following the technological advances that made the utilization of such systems cost effective, (3) Advances in numerical analysis methods and use of Artificial Intelligence applications in investigating performance and effectiveness of various systems, and (4) Integrating the Photovoltaic/Thermal collectors with heat pumps for simultaneous heat and power generation resulting in improved performance and reliable operation of systems under severe operating conditions.

This study presents a detailed three-dimensional numerical investigation of the optimum thermoelectric geometry in a hybrid concentrated photovoltaic-thermoelectric system under varying weather conditions. Four different thermoelectric leg geometries are considered and their effects on the performance of the hybrid system are studied. The effects of thermoelectric leg height, cross-sectional area and ceramic height on the hybrid system performance are investigated. Furthermore, the effect of convective heat transfer coefficient on the hybrid system performance is studied. The performance of the hybrid system with optimized thermoelectric geometry is compared with that of the hybrid system with original geometry for summer climatic conditions in London, United Kingdom for a duration of 24 h. Results show that thermoelectric geometry optimization can reduce significantly, the negative impacts of the variable weather conditions on the hybrid system performance. Furthermore, results show that the maximum hybrid system power output density with the optimized thermoelectric geometry decreased by 48.29% when the original geometry is used. This study will provide useful insights into thermoelectric geometry optimization in a hybrid system and optimum thermoelectric geometry for performance enhancement.

An efficient low-carbon system is proposed to meet the heating and cooling demands of rural houses in cold regions. Mini-channel solar panels incorporating a novel multiple-throughout-flowing loop are used for heat collection, whilst a vapour injection air source heat pump (VI-ASHP) is innovatively combined with an underfloor heating and cooling system. To demonstrate the system, a multiple-throughout-flowing mini-channel solar thermal panel array of 36 m2 and a VI-ASHP of 40 kW heating capacity have been built and tested. Subsequently, mathematical models of the solar-assisted VI-ASHP system are established and compared with the experimental data. Based on the validated models, the energetic, economic and environmental performance is investigated under the typical weather conditions for a northern Chinese city (Taiyuan). The results indicate that, for a common rural house employing the proposed novel system, the proportion of the annual heat requirement, cooling load and hot water heating energy provided by solar thermal energy, photovoltaic energy and electricity from the power grid is 74.6%, 6.9%, and 18.5% respectively, thus giving a total energy supply proportion of 81.5% from solar energy. In addition, compared with a coal-powered system, our system has a cost payback period of 6.52 years and a life-cycle net cost saving of 56328.4RMB, thus the proposed system provides a greater economic performance. Furthermore, it can save 5tons of anthracite coal and reduce carbon emissions by 12.1tons annually. The proposed solar-assisted VI-ASHP has the potential to fulfil heating and cooling demands whilst reducing carbon emissions in northern China.

This paper presents a whole building energy modelling work incorporating a state-of-the-art indirect evaporative cooling system. The model is calibrated and validated with real-life empirical data, and is capable of representing actual performance of the system with high reliability. The investigated system is a novel super-performance Dew Point Cooler (DPC) with a guideless and corrugated Heat and Mass Exchanger (HMX). The DPC is modelled as part of the whole building energy model through detailed description of system and building characteristics at source code level. The developed model has been simulated in all different climates that an Indirect Evaporative Cooling (IEC) system can be operated, namely: subtropical hot desert, humid continental, Mediterranean, and hot desert climates. The performance predictions has been tested against experiments and numerical model of the same system, and a detailed investigation of modelling approaches to efficiently and effectively model aforementioned systems has been provided. The calibrated and empirically validated whole building energy model predicted the key performance parameters of the dew point evaporative cooling system with mean error values limited to 4.1%. The highest COP values recorded by experiments and whole building energy simulations were 51.1 and 49, respectively. The whole building energy model proved to better predict the performance of dew point evaporative cooler, when compared to numerical models, by incorporating the building-side parameters into the model. This modelling work paves the way toward detailed investigation of the advanced cooling systems within building context to achieve optimised performance of the system in wide range of buildings and operating conditions.

This thesis investigates a novel solar-assisted heat pump integrated phase change energy storage system. The defrosting performance of this system was studied experimentally and the results were compared with two traditionally used methods: reverse cycle defrosting (RCD) method and hot gas bypass defrosting (HGBD) method. The results show that the phase change energy storage system has superior performance compared with traditional defrosting methods. The indoor temperature drop recorded was relatively small and the defrosting time was 75% of the RCD system and 53% of HGBD system. The phase change energy storage system increased the condensation temperature which consequently increased the temperature difference of heat transfer resulting in higher conductivity in the defrosting progress. Compared with the method of RCD and the method of HGBD, the recovery time of the system was shortened by 90 and 160 seconds, respectively. The system works with low-temperature heat source and circulating water, which considerably reduces energy consumption, thereby improving the performance of the defrosting system. A further experimental study was also conducted on the heating performance and the results also indicated that the value of COP can reach up to 3.6 in daytime, and the indoor temperature can be stably maintained above 18°C throughout the day.

This paper introduces a state-of-the-art modelling technique to investigate the performance of solar assisted dehumidification and regeneration cycles. The dehumidification/regeneration system investigated in this study employs a solid adsorbent bed and enables use of both solar energy and returning warm air to deliver efficient dehumidification and regeneration of the treated air. Study of literature revealed a huge gap between model results and industrial performance of such systems. Hence, the modelling work presented in this paper employs Gaussian Process Regression (GPR) technique to close the gap between model outputs and real-life operation parameters of the system. An extensive amount of laboratory tests were also carried out on the dehumidification/regeneration system and model predictions were validated through comparison with experimental results. The model predictions were found to be in good agreement with experimental results, with maximum error not exceeding 10%. The GPR technique enables simultaneous analysis of a vast quantity of key system parameters derived from mathematical models and laboratory tests. The system parameters investigated in this study include: temperature, relative humidity and flow rate of process air, and temperature of regeneration air, solar radiation intensity, operating time, moisture extraction efficiency of the dehumidification cycle and moisture removal efficiency of the regeneration cycle. Investigation of both modelling and experimental results revealed that efficiencies of the both dehumidification and regeneration cycles decrease as relative humidity of the process air increases. The increase in regeneration temperature leads to an increase in regeneration efficiency whereas; it does not have a significant impact on the dehumidification efficiency. A similar trend was also observed when solar intensity were increased. The proposed technique reduced the complexity of model by eliminating the need for heat and mass tran

This study is pioneered in developing digital twins using Feed-forward Neural Network (FFNN) and multi objective evolutionary optimization (MOEO) using Genetic Algorithm (GA) for a counter-flow Dew Point Cooler with a novel Guideless Irregular Heat and Mass Exchanger (GIDPC). The digital twins, takes the intake air characteristics, i.e., temperature, relative humidity as well as main operating and design parameters, i.e., intake air velocity, working air fraction, height of HMX, channel gap, and number of layers as the inputs. GIDPC’s cooling capacity, coefficient of performance (COP), dew point efficiency, wet-bulb efficiency, supply air temperature and surface area of the layers are selected as outputs. The optimum values of aforementioned operating and design parameters are identified by the MOEO to maximise the cooling capacity, COP, wet-bulb efficiencies and to minimise the surface area of the layers in four identified climates within Köppen-Geiger climate classification, namely: tropical rainforest, arid, Mediterranean hot summer and hot summer continental climates. The system monthly and annual performances in the identified optimum conditions are compared with the base system and the results show the annual improvements of up to 72.75% in COP and 23.57% in surface area. In addition, the annual power consumption is reduced by up to 49.41% when the system is designed and operated optimally. It is concluded that identifying the optimum conditions for the GIDPC can increase the system performance substantially.

This paper presents a comparison of bottom up models that generate appliance load profiles. The comparison is based on their ability to accurately distribute load over time-of-day. This is a key feature of model performance if the model is used to assess the impact of low carbon technologies and practices on the network. No work has yet assessed models on this basis. In this work, the temporal characteristics of load are captured using histograms, and similarity between the histogram representations of measured and generated data is assessed using the Wasserstein distance. This is then applied to compare the results of three models, which were developed here by adopting approaches used in previous research. One is based on occupant presence, one on occupant activity, and one on empirical data. Typical statistical tests showed that the comparison method is robust and can be used for this purpose.

With EU support I'd lead a team of sustainability experts to develop and implement a motivational and trust gaining approach that brought global experts, city decision makers, industrial partners and stakeholders together to co-create a future sustainable city vision. This would be known as the ‘City-zen Roadshow’. An approach, widely published and implemented, and recognized by the European Commission as an example of best practice for its societal impact, replication and uptake. Over a five year period this sustainability Roadshow would visit nine cities across Europe, building up significant experience along the way in building international collaborations that are culturally, politically and economically diverse. The most notable being that of Nicosia on the island of Cyprus, the only divided city in Europe. Here I would build a ‘Bicommunal’ partnership of Chamber of Commerce Presidents, United Nations, Mayors, Ambassadors, Universities and numerous SME’s and various volunteer organisations. In recognition of this in July 2020, I would be invited back to Cyprus as a key speaker for their ‘The UNFICYP Youth Champions – Environment & Peace initiative’ (part of the United Nation's 75th anniversary celebration's) to discuss / present how that partnership was made, the experiences along the way, and what were the outcomes of their future city and island vision. The interactive audience would comprise young adults from both sides of the political divide originating from the Turkish and Greek Cypriot zones. Further information: A youth champion will learn about tackling key issues such as climate change and environmental degradation. You will find out more about the challenges that these issues pose to future generations across this island and to peace, overall. You will participate in trainings organized by prominent Cypriot and internationally recognized environmental groups/organizations, together with UNFICYP and you will be empowered to design and deliver campaign

High temperature heat exchangers are needed in various energy technologies to increase their efficiency. The article is devoted to the optimization of the design of a high-temperature air heater used in the integrated gasification combined cycle plant, developed in Ural Federal University. In the air heater, air with a pressure of 2 MPa after the cycle compressor is heated by coal combustion to a temperature of 900°C before it is fed into the combustion chamber of a gas turbine. The air heater is developed as a pulverized coal fired boiler with air heating in tubular radiation-convection heating surfaces. The authors propose a new design of a high-temperature air heater, which allows reducing the cost of the expensive high-temperature part of the unit 1.8 times compared with the previous design. A computer simulation of the boiler section is carried out to verify the proposed design solutions. © Published under licence by IOP Publishing Ltd.

roposes a novel heat pump system to efficiently utilize the exhaust air. The system has two heat sources: exhaust air and ambient air. It consists of a condenser, two parallel evaporators and compressors, and two throttle valves. The exhausted indoor air is first used to heat the refrigerant in the medium-pressure evaporator. The exhaust air at a reduced temperature is then mixed with the ambient air to heat the low-pressure evaporator. The advantages of the mixed air source heat pump (MASHP) with two-stage evaporation over a conventional exhaust air heat pump (EAHP) include a larger heating capacity, higher waste heat recovery and lower carbon emission. Besides, the exhaust air can be employed for defrosting without additional power consumption. Thermodynamic performance of the system is investigated. Comparison is made with a conventional EAHP and a directly mixed air source heat pump with single-stage evaporation. The results indicate that under the conditions of exhaust air temperature of 20 oC, mass flow rate of 1.0 kg/s and ambient temperature of 0 oC, the profits for the proposed MASHP, conventional EAHP and MASHP with single-stage evaporation are about 11.5, 5.1 and 3.7 pound/day, respectively.

Swift performance assessment of dehumidification systems, in design stage and while operation of the system is of substantial importance for commercialization and wide implementation of this technology. This paper presents a novel statistical model, employing Gaussian Process Regression (GPR) to investigate performance of a solar/waste energy driven dehumidification/regeneration cycle with a solid adsorbent bed. The statistical model takes thousands of operating conditions derived from a numerical model to predict the performance of the system. This predictive tool directly correlates the main operating parameters with the performance parameters of the system. The operating parameters considered in this study are: temperature, relative humidity and flow rate of process air, temperature of regeneration air, length of the desiccant bed, solar radiation intensity and operating time, and the selected performance parameters are: moisture extraction efficiency for the dehumidification cycle and moisture removal efficiency for the regeneration cycle. The model is evaluated by three metrics, namely: root mean square error (RSME), mean absolute percentage error (MAPE), and coefficient of determination (R2). The maximum RSME and MAPE for moisture extraction are only 0.045, 0.21%, and for moisture removal efficiencies are 0.082 and 0.39%, respectively, while the R2 value is derived as 0.97. The developed model is used to investigate the impact of four selected operating parameters on system performance. Additionally, the system performance is predicted for randomly generated operating conditions as well as warm and humid climates. The developed GPR model provides a swift and highly accurate predictive tool for design of the dehumidification systems and for commercialization of the investigated dehumidification systems.