Design and performance of energy-efficient solar residential house in Andorra

This paper describes the design and building technology details of a three-storey single family house located in the Pyrenees, in Andorra. The house is owned by the first author, and has been occupied since 2004. A combination of active and passive solar energy systems and night-time electricity are used to supply the heating and cooling demands. The main goal of this paper is to provide detailed design information and an evaluation of performance. Data provided includes site information and climate, basic design options and decisions, energy saving strategies and energy end use data. The house has been in use since 2003. This allows adequate performance data to be presented and evaluated. Some general results and initial design problems are discussed.     

Performance evaluation of photovoltaic thermal solar air collector for composite climate of India

The objective of present study is to evaluate the performance of the photovoltaic (PV) module integrated with air duct for composite climate of India. In this case, thermal energy is produced along with electrical energy generated by a PV module with higher efficiency. An analytical expression for an overall efficiency (electrical and thermal) has been derived by using energy balance equation for each component. Experimental validation of thermal model of hybrid photovoltaic/thermal (PV/T) system has also been carried out. It has been observed that there is a fair agreement between theoretical and experimental observations. Further it is concluded that an overall thermal efficiency of PV/T system is significantly increased due to utilization of thermal energy in PV module.     

Performance optimization of evacuated tube collector for solar cooling of a house in hot climate

Evacuating the space connecting cover and absorber significantly improves evacuated tube collector (ETC) performance. So, ETCs are progressively utilised all over the world. The main goal of current study is to explore ETC thermal efficiency in hot and severe climate like Kuwait weather conditions. A collector test facility was installed to record ETC thermal performance for one-year period. An extensively developed model for ETCs is presented, employing complete optical and thermal assessment. This study analyses separately optics and heat transfer in the evacuated tubes, allowing the analysis to be extended to different configurations. The predictions obtained are in agreement with experimental. The optimum collector parameters (collector tube length and diameter, mass flow rate and collector tilt angle) are determined. The present results indicate that the optimum tube length is 1.5 m, as at this length a significant improvement is achieved in efficiency for different tube diameters studied. Finally, the heat generated from ETCs is used for solar cooling of a house. Results of the simulation of cooling system indicate that an ETC of area 54 m², tilt angle of 25° and storage tank volume of 2.1 m³ provides 80% of air-conditioning demand in a house located in Kuwait.     

Assessment of solar emissions in the climate of Iraq for efficient multifunctional disposal

The concept of solar-hydrogen energy today provides optimal solutions in light of the climate agenda for all geographic areas of the globe.Iraq's geographical location and climate conditions predetermine ample opportunities for renewable sources, namely solar energy. High air temperatures, the prevailing number of sunny days recorded annually in the region, create a favorable technical platform for the implementation of thermal processes based on the utilization of incoming research. Therefore, for the design of solar plants and in the future, a reliable estimate of solar energy resources is required to determine the generated power depending on seasonal changes. Theoretical methods of calculating the incoming radiation flow for a particular area do not have the required accuracy for a number of reasons, the main of which is the permanent state of cloud cover. Only taking into account the actual climatic conditions for the construction areas under consideration on the basis of long-term actinometric observations gives a fairly accurate distribution of solar energy. The absence of such information in full implies forecasting of resource availability, including for areas not covered by observation systems. Given these limitations, an analysis of the average monthly daily solar radiation revenues for densely populated areas of Iraq is provided. On the basis of actinometric information of many years of observations, dependencies were obtained to determine the solar energy coming at statistical clouds per day per 1 m² of horizontal surface of the area, taking into account its latitude and serial number of the month of the year. The equations allow to fulfill the forecast of the area irradiation for the design of solar plants, to justify the subsequent efficiency of the alternative system, as well as the level of possible replacement of traditional resources and the degree of reduction of their consumption. On the basis of the calculated data, it is possible to justify the most expedient scheme of solar energy utilization depending on the available resources and to select the structures of radiation sensing devices required for climatic conditions for the solved tasks. In view of the analysis of solar energy distributions and average monthly outdoor air temperatures in Iraq, two types of thermal solar plants have been recommended for use, which may have additional circuits for generating electricity and cold. In addition, the fixed irradiation potential of the territories makes it possible to carry out an effective passive transmission to maintain the thermophilic mode of anaerobic fermentation of organic waste. In this case, environmentally friendly utilization of carbon-containing substrates is accompanied by an increase in the rate of formation of biogas, and therefore hydrogen, without the use of traditional heat supply to reactors.     

Computer model and its validation for prediction of storage effect of water mass in a greenhouse: a transient analysis

In the present paper, an attempt has been made to develop a computer model based on transient analysis of the greenhouse. The model predicts room air temperature, storage water temperature and the thermal energy storage effect of a water mass in a low cost, passive greenhouse. Analytical expressions, based on an energy balance for each component, have been derived in terms of climatic as well as design parameters. Numerical computations have been done on typical days for the months from December 1999 to June 2000 at New Delhi. It has been observed that (i) there is a significant thermal energy storage effect of the water mass on room temperature and (ii) TLL, which is found to decrease with an increase in the mass of storage water, varies with month of year. An experimental validation of the developed model has also been demonstrated. The predicted room and water temperature show fair agreement with experimental values.     

Evaluation of solar radiation and its application for photovoltaic/thermal air collector for Indian composite climate

In this paper, an attempt has been made to evaluate cloudiness/haziness and atmospheric transmittance factors for the composite climate of New Delhi, India by considering the hourly data of global and diffuse radiation obtained for (i) the city region, experimentally observed and (ii) the flat land region obtained from the Department of Indian Meteorology, Pune. Cloudiness/haziness factor for the two models have been determined using simple regression analysis for clear sky condition for New Delhi. The comparison between the cloudiness/haziness and atmospheric transmittance factors for the composite climate of New Delhi for both the models and regions have been made. It has been observed that the cloudiness/haziness and atmospheric transmittance factors obtained by both models gave fair agreement within an accuracy of 0.57%. It has also been observed that there is a significant effect of region on beam and diffuse radiation due to cloudiness/haziness factors as expected. Further the data of solar radiation obtained from the Department of Indian Meteorology, Pune, have been used to evaluate the monthly performance of photovoltaic thermal (PV/T) air collector. It has been found that an overall thermal efficiency and exergy efficiency of PV/T air collector were about 50 and 14%, respectively. Copyright © 2006 John Wiley & Sons, Ltd.     

The impact of rate design and net metering on the bill savings from distributed PV for residential customers in California

Net metering has become a widespread mechanism in the U.S. for supporting customer adoption of distributed photovoltaics (PV), but has faced challenges as PV installations grow to a larger share of generation in a number of states. This paper examines the value of the bill savings that customers receive under net metering, and the associated role of retail rate design, based on a sample of approximately two hundred residential customers of California's two largest electric utilities. We find that the bill savings per kWh of PV electricity generated varies by more than a factor of four across the customers in the sample, which is largely attributable to the inclining block structure of the utilities' residential retail rates. We also compare the bill savings under net metering to that received under three potential alternative compensation mechanisms, based on California's Market Price Referent (MPR). We find that net metering provides significantly greater bill savings than a full MPR-based feed-in tariff, but only modestly greater savings than alternative mechanisms under which hourly or monthly net excess generation is compensated at the MPR rate.     

A multi-criteria evaluation of policy instruments for climate change mitigation in the power generation sector of Trinidad and Tobago

Even as small island developing states (SIDS) like Trinidad and Tobago (T&T) increase industrialization and grapple with the challenges of increased pollution, few studies provide guidance to policy makers of such countries on appropriate policy measures and instruments that can be implemented to mitigate greenhouse gas emissions. Here we apply a multi-criteria evaluation methodology to ascertain preferences for policy measures and instruments in the power generation sector. Four broad policy measures and twelve policy instruments are assessed on criteria of environmental performance, feasibility of implementation and political acceptability. This method proves useful in T&T, since typical to many SIDS, the intensive data required by other policy assessment methods is unavailable. Results indicate little difference in preference among the four policy measures thereby indicating that a multi-pronged approach on several policy fronts is required. The most preferred policy instruments to operationalize measures included provision of subsidies for energy saving technologies, creating an industry wide carbon trading scheme and implementing a feed-in tariff to increase the use of renewable energy sources. This study therefore provides specific insights for policy makers in Trinidad and Tobago while also providing power generation sector specific guidance to other rapidly industrializing small island developing states.     

Modeling, design and thermal performance of a BIPV/T system thermally coupled with a ventilated concrete slab in a low energy solar house: Part 2, ventilated concrete slab

This paper is the second of two papers that describe the modeling and design of a building-integrated photovoltaic-thermal (BIPV/T) system thermally coupled with a ventilated concrete slab (VCS) adopted in a prefabricated, two-storey detached, low energy solar house and their performance assessment based on monitored data. The VCS concept is based on an integrated thermal-structural design with active storage of solar thermal energy while serving as a structural component - the basement floor slab (∼33 m²). This paper describes the numerical modeling, design, and thermal performance assessment of the VCS. The thermal performance of the VCS during the commissioning of the unoccupied house is presented. Analysis of the monitored data shows that the VCS can store 9-12 kWh of heat from the total thermal energy collected by the BIPV/T system, on a typical clear sunny day with an outdoor temperature of about 0 °C. It can also accumulate thermal energy during a series of clear sunny days without overheating the slab surface or the living space. This research shows that coupling the VCS with the BIPV/T system is a viable method to enhance the utilization of collected solar thermal energy. A method is presented for creating a simplified three-dimensional, control volume finite difference, explicit thermal model of the VCS. The model is created and validated using monitored data. The modeling method is suitable for detailed parametric study of the thermal behavior of the VCS without excessive computational effort.     

Energy and economic assessment of desiccant cooling systems coupled with single glazed air and hybrid PV/thermal solar collectors for applications in hot and humid climate

This paper presents a detailed analysis of the energy and economic performance of desiccant cooling systems (DEC) equipped with both single glazed standard air and hybrid photovoltaic/thermal (PV/t) collectors for applications in hot and humid climates. The use of ‘solar cogeneration’ by means of PV/t hybrid collectors enables the simultaneous production of electricity and heat, which can be directly used by desiccant air handling units, thereby making it possible to achieve very energy savings. The present work shows the results of detailed simulations conducted for a set of desiccant cooling systems operating without any heat storage.System performance was investigated through hourly simulations for different systems and load combinations. Three configurations of DEC systems were considered: standard DEC, DEC with an integrated heat pump and DEC with an enthalpy wheel. Two kinds of building occupations were considered: office and lecture room. Moreover, three configurations of solar-assisted air handling units (AHU) equipped with desiccant wheels were considered and compared with standard AHUs, focusing on achievable primary energy savings.The relationship between the solar collector’s area and the specific primary energy consumption for different system configurations and building occupation patterns is described. For both occupation patterns, sensitivity analysis on system performance was performed for different solar collector areas. Also, this work presents an economic assessment of the systems. The cost of conserved energy and the payback time were calculated, with and without public incentives for solar cooling systems. It is worth noting that the use of photovoltaics, and thus the exploitation of related available incentives in many European countries, could positively influence the spread of solar air cooling technologies (SAC). An outcome of this work is that SAC systems equipped with PV/t collectors are shown to have better performance in terms of primary energy saving than conventional systems fed by vapour compression chillers and coupled with PV cells.All SAC systems present good figures for primary energy consumption. The best performances are seen in systems with integrated heat pumps and small solar collector areas. The economics of these SAC systems at current equipment costs and energy prices are acceptable. They become more interesting in the case of public incentives of up to 30% of the investment cost (Simple Payback Time from 5 to 10 years) and doubled energy prices.     

中国石油广西石化千万吨级炼厂“节能减排”设计

介绍了中国石油在南方布点建设的大型炼油企业——广西石化1000×10^4t／a炼油项目的用能特点。分析比较了该项目的能耗指标,该项目全厂炼油部分综合能耗为74．69kg标油／t原油,单位因数能耗为10．01kg标油/（t原油·能量因数）,达到了国内外先进水平。介绍了该项目主要的节能、节水措施以及“节能减排”预期效果     

大中型商场电气照明节能设计措施

针对大中型商场的照明设计中存在的问题进行分析,提出减少配电线路的损耗、选用合理的照度、合理布局与选择灯具、推广使用节能的电子镇流器、积极采用新型光源和采用照明自动控制系统等措施。     

大型汽轮机的冷端优化设计及其在大唐东营1 000 MW二次再热机组上的应用

火电机组节能不仅仅是大量新技术的简单堆积,更需要创新的理念.提出大冷端的新理念以及宽负荷节能的技术思想.基于技术经济比较,充分挖掘当地的循环水条件,完成了东营项目的深度优化设计,在国内外首次采用6缸6排汽汽轮机,其不同负荷下的平均热耗降低100 kJ/(kW·h)以上,标准煤单价为700元/t的条件下所增加投入的回收期...