Experiment and Analytical Studies Jujube Drying by the Solar Assisted Convection Drying

An experimental setup, a mini-cabinet with reflector at its top, has been designed to study the drying process of jujube fruit by the convection and the solar radiation with hot air convection. The research experimentally investigated the drying characteristics and behavior of heat and mass transfer. Also, drying curves were analyzed. It demonstrated that solar energy could play an important role in promoting heat and mass transfers and saves energy consumed. The optimum conditions of appropriated temperature and humidity were obtained to save energy in solar energy convection drying process.

Incorporating Thermal Storage Into a SEGS Plant Using TRNSYS: A Status Report

Two new preliminary component types were developed for the transient simulation program TRNSYS with IISiBat that models three different types of sensible thermal storages for analysis with use in a solar electric generating system (SEGS) simulation. One component containing a fully mixed, a stratified and a plug flow tank model options has been developed such that the input and parameter specifications are similar so that all three models could be easily placed into one component type. A single, cylindrical direct storage tank with one inlet and one outlet that evaluates fluid properties as a function of temperature is representative for all three models. The second component is a storage controller that passes along pertinent charging, dwell or discharging information to the storage and integrates the storage into a given SEGS model. Results were generated for each storage tank integrated into a SEGS VI simulation model for temperature distribution and power generation.

Solar Radiation Over the Caribbean Island of Puerto Rico

Solar radiation was measured and recorded on a 5-minute, hourly and daily basis at a number of sites on the Caribbean island of Puerto Rico (located from 18° to 18° 30’N latitude and from 65° 30’ to 67° 15’W longitude) over a 24 calendar month time frame. The global solar radiation was measured at four sites (namely: Aguadilla, Ponce, Gurabo, and San Juan). The global solar radiation data was measured by an Eppley Precision Spectral Pyranometer (model PSP) mounted on a horizontal surface. This pyranometer is sensitive to solar radiation in the range of 0.285 ≤ λ ≤ 2.8 μm wavelengths. Statistical analysis such as the daily average, monthly average hourly, monthly average daily, and annual average daily global radiation are presented in this paper. Despite its small size, a 13 percent variation in the global solar radiation has been observed within the island. Reasonable solar radiation values, for solar energy conversion system installation, seem to exist at and possibly around Aguadilla.

Evacuated Tube Heat Pipe Solar Collectors Applied to Recirculation Loop in a Federal Building: SSA Philadelphia

This paper describes design, simulation, construction and measured initial performance of a solar water heating system (360 Evacuated Heat-Pipe Collector tubes, 54 m2 gross area, 36 m2 net absorber area) installed at the top of the hot water recirculation loop in the Social Security Mid-Atlantic Center in Philadelphia. Water returning to the hot water storage tank is heated by the solar array when solar energy is available. This new approach, as opposed to the more conventional approach of preheating incoming water, is made possible by the thermal diode effect of heat pipes and low heat loss from evacuated tube solar collectors. The simplicity of this approach and its low installation costs makes the deployment of solar energy in existing commercial buildings more attractive, especially where the roof is far removed from the water heating system, which is often in the basement. Initial observed performance of the system is reported. Hourly simulation estimates annual energy delivery of 111 GJ/year of solar heat and that the annual efficiency (based on the 54 m2 gross area) of the solar collectors is 41%, and that of the entire system including parasitic pump power, heat loss due to freeze protection, and heat loss from connecting piping is 34%. Annual average collector efficiency based on a net aperture area of 36 m2 is 61.5% according to the hourly simulation.

A Hybrid Method for Estimating Natural Lighting Potential in Buildings

This paper describes data and algorithms to estimate typical average interior illuminance from daylighting using a hybrid of Hay, Davies, Klucher, Reindl (HDKR) method for calculating total solar radiation on a tilted surface and the Illuminating Engineering Society (IES) Lumen Method for estimating interior illuminance from daylighting. This hybrid algorithm, in conjunction with typical meteorological data, directly accounts for shading and typical local cloud cover effects on an hour-by-hour basis, which is difficult to do using the IES sky-cover or sky-ratio methods. Several experiments show reasonable agreement between measured and calculated results. Case study examples demonstrate of use of the method, when incorporated into software, to quickly analyze daylighting potential in industrial facilities, and the use of this information to develop specific recommendations for cost-effectively reducing lighting energy use in industrial facilities by improving the utilization of natural lighting.

Modeling and Design of Direct Solar Steam Generating Collector Fields

The direct steam generation (DSG) is an attractive option regarding the economic improvement of parabolic trough technology for solar thermal electricity generation in the multi megawatt range. According to [1] and [2] a 10% reduction of the LEC is expected compared to conventional SEGS like parabolic trough power plants. The European DISS project has proven the feasibility of the DSG process under real solar conditions at pressures up to 100 bar and temperatures up to 400°C in more than 4000 operation hours [3]. In a next step the detailed engineering for a pre-commercial DSG solar thermal power plant will be performed. This detailed engineering of the collector field requires the consideration of the occurring thermohydraulic phenomena and their influence on the stability of the absorber tubes. A design tool has been developed at DLR calculating all relevant process parameters including pressure drop, temperature field and stress in the absorber tubes. The models implemented in this design tool have been validated in detail at the DISS test facility under real DSG conditions for pressures between 30 and 100 bar and inner diameters between 50 and 85 mm. The models have been implemented into a MATLAB® program to allow for a first quick determination of critical process conditions. Once critical process conditions have been identified the FEM package ANSYS® is used for a detailed investigation. This article summarises the models used and shows the design procedure for a DSG collector field. The design program has proven to be a reliable tool for the detailed design of DSG collector fields.

Feasibility of Usage Possibility in Turkey of Solar Driven Ejector-Absorption Cooling System

It appears that solar assisted refrigeration systems are a promising alternative to the conventional electrical driven units. Their main advantages are the reduction of peak loads for electricity utilities, the use of zero ozone depletion impact refrigerants, the decreased primary energy consumption, and decreased global warming impact. In this study, we have investigated the possibility of using ejector-absorption cooling systems (EACS) in Turkey. In addition, this study determines whether or not required heat for generator of EACS can be obtained from solar energy in Turkey. There are two important reasons to explain the use of EACS in Turkey. One is that the production and use of the CFCs and HCFCs will be phased out according to Montreal Protocol. The second is that, in Turkey, solar energy potential is very high due to its location in the northern hemisphere with latitudes 36–42°N and longitudes 26–45°E, the yearly average solar radiation is 3.6 kWh/m2 day, and the total yearly radiation period is ∼2610 h. The radiation data and sunshine duration information collected since 2000 for 17 cities are used for analysis in different regions of Turkey. For maximum coefficient of performance (COPmax) conditions of EACSs operated with aqua-ammonia, it is found that required optimum collector surface area was defined by using the meteorological data. In addition since the system can be used throughout the year, required minimum energy for auxiliary heater was also calculated. It is shown that the heat gain factor (HGF) varies in the range from 0.5 to 2.68 for the all the seasons in the selected cities. The maximum HGF is 2.68 for Van in July. This study shows that there is a great potential for utilisation of solar cooling system for domestic heating/cooling applications in Turkey.

Performance Evaluation of an IC Engine (SI) Using Biogas as Fuel With Petrol Blends: A Case Study

Biogas is the term used for the gas made from the natural decomposition of Organic (plant or animal) materials. It is Produced when the materials are digested by bacteria in a situation where little or no air is present (anaerobic digestion). Biogas consisting of approximately two-thirds methane (CH4) and one-third carbon dioxide (CO2) burns well and can be used to provide energy in the form of heat or electricity. The main practical sources of biogas are sewage, animal manure and the organic materials in household refuse or industrial waste. Like other renewable energy sources, biogas is a stored form of solar energy (since it originates from plants which used the sun’s energy to grow). An experimental evaluation was carried out to compare the performance of an IC engine (SI) Using Biogas as fuel blended with petrol in different proportions to that of only petrol as fuel. The performance study carried out in a four cylinder SI engine shows that this can better be used as an automotive fuel with a comparatively much lesser cost than the conventional fuels. The results show that because of the low calorific value of biogas the thermal efficiency is lesser than that of petrol and remains same at low and high out puts. Same is the case for volumetric efficiency. Biogas is an excellent and economical fuel for both petrol and diesel engines. However the power obtained is less than that of liquid fuel. Biogas is a cheaper and better fuel for cooking, lighting and running engines.

Emission Allowances for Renewable Energy and Energy Efficiency Projects

Allowance trading programs represent an opportunity for the renewable and energy-efficiency industry to capitalize on the environmental benefits associated with their projects. By reducing or preventing emissions, renewable and energy-efficiency projects may qualify for emission allowances that can help sponsors justify their projects. Several federal, state, and international programs are venues for emissions documentation and trading. One program, an energy efficiency/renewable energy set-aside program, is described in this paper. A crucial element of an allowance trading program is the documentation and verification, or evaluation, of actual emission reductions. Thus, this paper also reviews the evaluation process that has been developed for an energy-efficiency and renewable-energy set-aside program and puts the process in context with methods outlined in the International Performance Measurement and Verification Protocol (IPMVP).

Analysis of Daylighting Benefits for Office Buildings in Egypt

This paper summarizes the results of a simulation analysis to determine the effectiveness of daylighting in reducing electrical energy consumption for office buildings in Egypt. Specifically, the impact on daylighting performance is investigated of window size, building size, daylighting control, and glazing type for three geographical locations in Egypt. It was determined that a window to wall area ratio of 0.20 minimizes the total annual electricity use for office buildings in three Egyptian locations, Cairo, Alexandria, and Aswan. A simplified analysis method is developed based on the analysis results to estimate the annual electrical energy savings attributed to daylighting.