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- Zhang, Xingxing, et al.
(författare)
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Socio-economic performance of a novel solar photovoltaic/loop-heat-pipe heat pump water heating system in three different climatic regions
- 2014
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 135, s. 20-34
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Tidskriftsartikel (refereegranskat)abstract
- This paper aimed to study the socio-economic performance of a novel solar photovoltaic/loop-heat-pipe (PV/LHP) heat pump water heating system for application in three different climatic regions, namely, cold area represented by London, warm area represented by Shanghai, and hot (subtropical) area represented by Hong Kong. This study involved prediction of the annual fossil-fuel energy saving, investment return period and carbon emission reduction of the new system against the traditional gas-fired and electrical boilers based water heating systems. An established dynamic model developed by the authors was utilised to predict the system’s energy performance throughout a year in the three climatic regions. A life-cycle analytical model was further developed to analyse the economic and environmental benefits of the new system relative to the traditional systems. Analyses of the modelling results drew out several conclusive remarks: (1) the system could achieve the highest energy efficiency when operating at the hot (subtropical) climatic region (represented by Hong Kong), enabling the heat output of as high as 922 kW h/m2 yr and water temperature of above 45 °C, while the grid power input is only 59 kW h/m2 yr; (2) the system is worth for investment when operating at the high energy charging tariff area (represented by London), with the cost payback periods of 8 and 5 years relative to the traditional gas-fired and electrical boilers based systems, respectively; (3) the system could obtain the most promising environmental benefits when operating in Shanghai where the energy quality (embodied carbon volume of per kW h energy) is relatively poor, enabling reduction in life-cycle carbon emissions of around 4.08 tons/m2 and 17.87 tons/m2 respectively, relative to the gas-fired and electrical boilers. Answer to such a question on which area is most suitable for the system application is highly dependent upon the priority order among the three dominating factors: (1) energy efficiency, (2) economic revenue, and (3) environmental benefit, which may vary with the users, local concerns and policy influence, etc. The research results will be able to assist in decision making in implementation of the new PV/thermal technology and analyses of the associated economic and environmental benefits, thus contributing to realisation of the regional and global targets on fossil fuel energy saving and environmental sustainability.
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- Alsufyani, Maryam, et al.
(författare)
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The effect of aromatic ring size in electron deficient semiconducting polymers for n-type organic thermoelectrics
- 2020
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 8:43, s. 15150-15157
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Tidskriftsartikel (refereegranskat)abstract
- N-type semiconducting polymers have been recently utilized in thermoelectric devices, however they have typically exhibited low electrical conductivities and poor device stability, in contrast to p-type semiconductors, which have been much higher performing. This is due in particular to the n-type semiconductors low doping efficiency, and poor charge carrier mobility. Strategies to enhance the thermoelectric performance of n-type materials include optimizing the electron affinity (EA) with respect to the dopant to improve the doping process and increasing the charge carrier mobility through enhanced molecular packing. Here, we report the design, synthesis and characterization of fused electron-deficient n-type copolymers incorporating the electron withdrawing lactone unit along the backbone. The polymers were synthesized using metal-free aldol condensation conditions to explore the effect of enlarging the central phenyl ring to a naphthalene ring, on the electrical conductivity. When n-doped with N-DMBI, electrical conductivities of up to 0.28 S cm(-1), Seebeck coefficients of -75 mu V K-1 and maximum Power factors of 0.16 mu W m(-1) K-2 were observed from the polymer with the largest electron affinity of -4.68 eV. Extending the aromatic ring reduced the electron affinity, due to reducing the density of electron withdrawing groups and subsequently the electrical conductivity reduced by almost two orders of magnitude.
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- Chen, Yaqi, et al.
(författare)
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Insight into the Extreme Side Reaction between LiNi0.5Co0.2Mn0.3O2 and Li1.3Al0.3Ti1.7(PO4)3 during Cosintering for All-Solid-State Batteries
- 2023
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Ingår i: Chemistry of Materials. - 1520-5002 .- 0897-4756. ; 35:22, s. 9647-9656
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Tidskriftsartikel (refereegranskat)abstract
- All-solid-sate batteries (ASSBs) with a NASICON-type solid-state electrolyte (SSE) of Li1.3Al0.3Ti1.7(PO4)3 (LATP) can be accepted as a promising candidate to significantly improve safety and energy density due to their high oxidation potential and high ionic conductivity. However, thermodynamic instability between the cathode and LATP is scarcely investigated during cosintering preparation for the integrated configuration of ASSBs. Herein, the structural compatibility between commercially layered LiNi0.5Co0.2Mn0.3O2 (NCM523) and LATP SSE was systematically investigated by cosintering at 600 °C. It is noticeable that an extreme side reaction between Li from NCM523 and phosphate from LATP happens during its cosintering process, leading to a severe phase transition from a layered to a spinel structure with high Li/Ni mixing. Consequently, the capacity of NCM523 is lost during the preparation of the NCM523-LATP composite cathode. Based on this, we suggested that the interface modification of the NCM523/LATP interface is valued significantly to inhibit this extreme side reaction, quickening the application of LATP-based ASSBs.
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- Han, Mengjie, et al.
(författare)
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A review of reinforcement learning methodologies on control systems for building energy
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The usage of energy directly leads to a great amount of consumption of the non-renewable fossil resources. Exploiting fossil resources energy can influence both climate and health via ineluctable emissions. Raising awareness, choosing alternative energy and developing energy efficient equipment contributes to reducing the demand for fossil resources energy, but the implementation of them usually takes a long time. Since building energy amounts to around one-third of global energy consumption, and systems in buildings, e.g. HVAC, can be intervened by individual building management, advanced and reliable control techniques for buildings are expected to have a substantial contribution to reducing global energy consumptions. Among those control techniques, the model-free, data-driven reinforcement learning method seems distinctive and applicable. The success of the reinforcement learning method in many artificial intelligence applications has brought us an explicit indication of implementing the method on building energy control. Fruitful algorithms complement each other and guarantee the quality of the optimisation. As a central brain of smart building automation systems, the control technique directly affects the performance of buildings. However, the examination of previous works based on reinforcement learning methodologies are not available and, moreover, how the algorithms can be developed is still vague. Therefore, this paper briefly analyses the empirical applications from the methodology point of view and proposes the future research direction.
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