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This paper presents the feasibility analysis of a small-scale low-temperature solar organic Rankine cycle power system. The heat transfer fluid for running the organic Rankine cycle system is hot water with a temperature of 120 °C provided by an array of evacuated tube solar collectors. The performance of the solar organic Rankine cycle system was investigated using two different working fluids over a wide range of the evaporation temperature. Technical and economic indicators such as the required solar collector aperture area, the total heat transfer surface area of the heat exchangers and the volume flow ratio between the outlet and inlet of the expander are among the key parameters used to evaluate the solar organic Rankine cycle. Thermolib toolbox 5.2 in conjunction with MATLAB/Simulink was used to predict the variation of the system performance. The results showed that the solar organic Rankine cycle system is able to achieve an overall system efficiency of 6.75% using a relatively low-temperature heat source. The results also showed that the solar organic Rankine cycle system requires smaller evacuated tube solar collector and heat exchanger areas when R245fa is used as the working fluid. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel cooling system with a simple design was developed. • The system is based on fluid piston machines and solar collector. • The system was tested on a solar radiation simulation test rig. • The experimental performance results of the system are analysed. • The prototype's performance is comparable to that of main existing technologies. The development of novel and improvement of existing technologies for utilising solar thermal energy for cooling purposes traditionally attracts increased attention in both industry and academia. This work presents the development of a novel cooling system with a simple design and direct utilisation of solar thermal energy. The cooling system combines a liquid piston engine and cooling machine and is driven by an evacuated tube solar collector. A prototype of such the system was designed, built and tested in laboratory conditions using a solar radiation simulator. Variations in pressures, temperatures, and the fluid piston oscillation amplitudes in the system during its operation were recorded, and the indicated power of the engine and cooling capacity of the system were determined for a range of operation and design parameters. For the heat input range of 700–900 W and the constant temperature of the cooling water equal to 26.0 °C, the engine indicated power and cooling capacity of the system varied in the range of 70.0–88.0 and 51.0–61.0 W. The corresponding indicated efficiency of the engine and cooling system were in the range of 10.0–9.7 and 7.2–6.7%. The temperature in the cooling chamber was registered in the range of 20.0–18.2 °C at an ambient temperature of 24.0 °C. The COP of the cooling machine decreased from 0.71 to 0.69. The system performance improved in tests with a constant heat input (700 W) and reducing cooling water temperature. For cooling water temperature reduction from 26.0 to 18.0 °C, the engine indicated power and cooling capacity of the system varied in the range of 70.0–111.9 and 51.0–72.0 W. The corresponding indicated efficiency of the engine and cooling system were in the range of 10.0–16.0 and 7.2–10.3%. The COP of the cooling machine decreased from 0.71 to 0.64. The temperature in the cooling chamber was registered in the range of 20.0–14.4 °C at an ambient temperature of 24.0 °C. Experimental results obtained using the system's initial design demonstrate that the engine has efficiency comparable to low-temperature steam and Organic Rankine Cycle turbines. The Coefficient of Performance of the system is similar to that of single-stage absorption chillers. [ABSTRACT FROM AUTHOR]

• Solar energy and PCM are used to augment the indoor steam curing process. • Mathematical model of the curing process is developed. • Comparison with experiments confirms the accuracy of the mathematical modelling. • Benefits of the proposed technology are quantitively demonstrated. Steam is used to provide heating and moisture in the curing process for the production of precast concrete (PC) construction elements. The generation of steam requires large amounts of fossil fuels. This study considers the incorporation of solar thermal energy into the steam curing of PC construction elements for reducing the need for fossil fuels and associated CO 2 emissions. For this purpose, the board made of composite phase change material covers the inner surface of the main sun-facing wall in the heating & curing building. The PCM board is heated by sun rays and accumulates thermal energy during the PCM's phase transition, and this energy then is released to the indoor environment of the building, reducing the amount of steam required to maintain a certain level of temperature during the curing process. The energy consumption simulation software, EnergyPlus, and two physical models (built on the scale of 1:3) were used to study the effects of two different PCMs on the thermal performance of such new type of heating & curing buildings. Composite PCMs considered were GH-33 and GH-37 with 33 and 37 °C melting temperatures developed by the research team. The theoretical and experimental results are in good agreement and demonstrate that, compared to the GH-33, GH-37 PCM increases the temperature of the inner surface of the main sun-facing wall and the upper surface temperature of the PC construction element by 3.4 and 1.4 °C, respectively. The heat accumulation and discharge rates also were greater by 62%. For the investigated design of the building and given location in China, the deployment of studied PCM wall panels results in a reduction in the annual energy consumption and CO2 emissions by 58.6 GJ and 5 tons, respectively. The method developed for applying solar energy and selecting PCMs for augmenting steam curing of PC construction elements can be deployed in different geographical regions. [ABSTRACT FROM AUTHOR]

• The laboratory and full-scale prototypes of the novel solar air collector were tested. • Fuel economy achieved in tests varies from 11% to 81% depending on weather conditions. • The increased concentration ratio of about 1.4 was obtained without a sun-tracking device. • The mathematical model of the collector was validated against experimental results. • The model was used to define the rational design parameters of the full-scale prototype. The application of greenhouse technologies is rapidly expanding in China and other regions of the world with the continental climate. Such technologies are characterized by a considerable consumption of fossil fuels, especially in winter periods. Various renewable energy technologies are used to reduce the energy demand in greenhouses, including solar heating. Simpler designs of water or air solar collectors are preferred without sun-tracking devices and reduced dimensions and weight. In this work, a novel solar multi-surface air collector with double-receiver tubes, which does not require a sun-tracking device is proposed and has increased concentration ratio and sun rays convergence and reduced thermal losses. The laboratory and full-scale prototypes of the proposed novel collector were manufactured and tested in laboratory conditions during the December-January period as a part of the greenhouse with the active-passive ventilation wall and latent thermal storage, located in the Beijing Region. Results of experiments demonstrate that the solar collector increases the average temperatures of the greenhouse north wall inner surface by 7.5 °C, indoor air during the night-time by 1.8 °C and indoor soil by 1.5 °C. The novel collector provided active heat gains of 11.831 GJ during the December-January period and satisfied from 11% to 81% of the heat load. A lumped parameter mathematical model of the proposed collector was developed, and the comparison of simulation results and experimental data demonstrate its high accuracy in prediction of the collector performance. The model was used to study the influences of outdoor meteorological parameters, air velocity in the receiver tubes and their length on the performance of the collector. This data was used to determine the rational design parameters and air velocity of the full-scale collector. The model was also used to rationalize the variation of air velocity in the receiver tube during the day. [ABSTRACT FROM AUTHOR]