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Abstract This paper presents preliminary results from the first nine months of monitoring the Oxford Solar House (OSH) which was built, in particular, to evaluate the potential for photovoltaics to contribute cost effectively to domestic energy supply in the UK. The house was built in a south facing site with good solar access. It has a 4kW PV system integrated into the roof structure and a 5m 2 solar thermal domestic hot water pre-heat. The house was designed to require a minimum of energy for heating, cooling and lighting, therefore optimizing the significance of the contribution of the solar electric supply. The performance of the PV system is presented, as well as an analysis of the whole design strategy to minimize energy loads.

Direct characterisation of the annual performance of solar thermal and heat pump systems using a six-day whole system test

Abstract The Angstrom-Prescott (A-P) model, a highly rated model, has been widely used to estimate global solar radiation (H) at daily or monthly scales in different locations around the world. However, few studies focused on the interchangeability of the A-P coefficients at different time scales, especially finer scales. The objectives of this work were to determine the A-P coefficients at daily (TS1), 5-day (TS2), 10-day (TS3), and monthly (TS4) time scales and to investigate the variations of the A-P coefficients caused by the time intervals and how this variations impacts on H estimation. Long-term records of H (1961-2000) from a total of 15 stations in the Yangtze River basin were used in the present study. The model performance was evaluated using root mean squared error (RMSE), coefficient of determination (R2), mean absolute difference (MAD), and Pearson coefficient. Better fit were found at time scales of TS2 and TS3 (R2 = 0.86 and 0.84, respectively) between the observed and predicted H. For each station, slight differences existed between the coefficients at the studied time scales. In general, the difference in coefficients increased with the increased of time interval from TS1 to TS2, TS3 and TS4. The largest differences in the coefficients were found between TS1 and TS4. Nevertheless, further analysis demonstrated that the coefficients calibrated at finer time scale could be applied to estimate H at larger time scales with an acceptable accuracy, and vice versa. The results have significant implications to facilitate the calibration and choice of the A-P coefficients.

Solar reactors designed and constructed for thermochemical applications present different configurations and general performance. The selection of a solar reactor that optimizes a particular process is always a difficult challenge. This work studies two types of reactor configuration by means of a comparative experimental analysis. It was employed a solar device, which is able to operate as fixed reactor with packed bed samples and as rotary kiln. The reduction of CuO into Cu2O was tested under both operation modes, due to its proved potential and interest as thermochemical storage material. It was found that heat transfer was hindered in static experiments limiting the fraction of reactive sample. Thermal gradients of about 200 °C were found in the packed bed through thermocouple and IR camera measurement. Heating rates and total fed energy must be restricted at the risk of front of the sample to melt, resulting in several operation drawbacks. In contrast, mixing conditions in rotary kilns allowed for higher heating rates and led to homogenous sample temperature. Maximum reaction yields in stationary mode did not overpass 14% while it was achieved more than 80% in rotary mode at temperatures about 860 °C. Thermal efficiencies were very limited in both operation modes due to the high thermal inertia of the solar reactor. Because rotary mode admitted much more energy, its thermal efficiency was even lower than static. A solution to increase rotary kilns thermal efficiency is working in continuous mode.

Fuel gas production from biomass using circulating fluidised bed technology is presented in our laboratory. This improved technical concept is aiming at producing high quality gas, in terms of low tar level and particulates carried out in the fuel gas, and overall emissionstextquoteright reduction associated with fuel gas combustion, as well as stable and reliable operation with the minimum fluctuations in the producer gas volume and composition. Based on this concept, a characteristic theoretical modelling approach involving hydrodynamics, chemical reaction kinetics, and energy balance is accordingly discussed. In addition, very preliminary experimental results from a laboratory-made test rig are also given.

With increased global concerns on climate change, the need for innovative spaces which can provide thermal comfort and energy efficiency is also increasing. This paper analyses the effects of transitional spaces on energy performance and indoor thermal comfort of low-rise dwellings in the Netherlands, at present and projected in 2050. For this analysis the four climate scenarios for 2050 from the Royal Dutch Meteorological Institute (KNMI) were used. Including a courtyard within a Dutch terraced dwelling on the one hand showed an increase in annual heating energy demand but on the other hand a decrease in the number of summer discomfort hours. An atrium integrated into a Dutch terraced dwelling reduced the heating demand but increased the number of discomfort hours in summer. Analysing the monthly energy performance, comfort hours and the climate scenarios indicated that using an open courtyard May through October and an atrium, i.e. a covered courtyard, in the rest of the year establishes an optimum balance between energy use and summer comfort for the severest climate scenario.

Abstract Whilst energy can be efficiently extracted from waves by a device exhibiting sloped motion, sustaining that performance in a deep water environment would conventionally rely on a costly support structure. Introduced herein, the WaveTrain device provides an alternative approach to retain the benefits of sloped motion, using a series of joints and struts to mechanically interconnect a series of sloped modules, each of which houses an internal water column to allow reaction against the surrounding water inertia. With a view to maximal power extraction in a real wave climate, this paper presents an optimisation of key parameters associated with the geometry and mass distribution. This relies upon an efficient hydrodynamic model, whose development is presented, particularly with respect to the use of ‘generalised’ modes to model hinges, for which a somewhat didactic treatment is given. A genetic algorithm, tailored specifically to handle the discontinuous parameter space and the numerical hydrodynamic model, is then used to identify design criteria that are essential for optimal power extraction. Five necessary but not sufficient criteria are presented, in addition to guidance regarding the remaining parameters, which is used to briefly highlight the potential benefits for the practical engineering design.

Abstract A novel model of the combined cycle of a solar-powered adsorption–ejection refrigeration system (CCSPAERS) is established. By analyzing the theory of this system and its thermodynamics, together with numerical simulation, it is found that it is a feasible method to overcome the intermittent character of a single bed solar adsorption refrigeration system. The estimated coefficient of performance for this combined cycle is about 0.4 under the following operating conditions: condensing temperature 313 K, evaporating temperature 283 K, regenerating temperature 393 K and desorbing temperature 473 K, using zeolite 13X–water as the pair. The higher desorbing temperature can be obtained when a vacuumed tube adsorber or a CPC adsorber is used.