Accepted Manuscripts

Gustavo S. Böhme, Eliane A. Fadigas, Julio Romel Martinez-Bolanos and Carlos E. Tassinari
J. Sol. Energy Eng   doi: 10.1115/1.4042547
Micrositing wind flow modeling presents one of the most relevant uncertainties in the project of wind power plants. Studies in the area indicate that the average uncertainty related to this item varies between 2.4% and 8% of the Annual Energy Production (AEP). The most efficient form to mitigate this uncertainty is to obtain additional measurements from the site. This can be achieved by installing met masts and by applying short-term remote sensing campaigns (LIDAR and SODAR). Ideally, measurement campaigns should have at least one complete year of data to capture seasonal changes in the local wind behavior and to increase the long-term representation of the sample. However, remote sensing is frequently performed in reduced periods of measurement, coming down to months or even weeks of campaign. The main contribution of this paper is to analyze whether short term remote sensing measurements contribute to the development of wind power projects, given the associated uncertainties due to low representativeness of the reduced data sample. This study was performed using over 60 years of wind measurement data. Its main findings indicate that the contribution of short term remote sensing campaigns vary depending on the complexity of the local terrain, and the respective uncertainty related to horizontal and vertical extrapolation of micrositing models. The results showed that in only 30% of the cases, a 3-month measurement campaign reduced the projects overall uncertainty. This number increases to 50% for a 6-month campaign, and 90% for a 10-month campaign.
TOPICS: Wind power, Uncertainty, Wind, Wind farms, Flow (Dynamics), Energy generation, Modeling
Jitender Singh Shekhawat, Dilip Sharma, M P Poonia and Hemant Raj Singh
J. Sol. Energy Eng   doi: 10.1115/1.4042524
This work aims at providing insight into developmental and operational experience of an innovative milk cooler which uses solar thermal energy for cooling of fresh milk by way of vapour absorption refrigeration system (VARS). The system uses CPC solar collector(s) producing medium temperature that is desired to provide required thermal energy to the generator of VARS. However, mismatch between the time of availability of solar energy and cooling period of milk raises a demand of integrating thermal storage to this system for use of thermal energy at appropriate times. The novelty of this work is development of experimental setup and its operation as innovative design to meet the requirement and possible model for the industry to operate and grow using the suggested system. The design, while addressing the problem of grass root level people for generation of income, also helps in reducing the carbon foot-print of milk industry and helping the world environment as a whole.
TOPICS: Solar energy, Cooling, Thermal energy, Design, Refrigeration, Solar collectors, Temperature, Carbon, Absorption, Solar thermal power, Generators, Thermal energy storage
Zachary Springer and M. Keith Sharp
J. Sol. Energy Eng   doi: 10.1115/1.4042452
The potential of sky radiation (SR) to serve the latent space cooling loads was evaluated. Using ASHRAE standard 55 comfort limits (room temperature 22oC, relative humidity 60%, dew-point temperature 13.9oC), condensation was the chosen mechanism for humidity reduction. Typical meteorological year (TMY3) weather data was used for eleven ASHRAE climate zones. Three values of load-to-radiator ratio LRR (infiltration/ventilation volume flow rate times the ratio of building floor area to radiator area) were evaluated: 0.35, 3.5 and 35 m/hr. Three thermal storage cases were considered: 1. Annual cooling potential, 2. Diurnal storage, and 3. Minimum storage capacity to serve the entire annual load. Six SR temperatures Trad = 13.9 to -26.1oC were tested. Even in the most challenging climates, annual SR potential exceeded the total sensible and latent cooling load, at least for the lowest LRR and highest Trad. For diurnal storage, SR served less than 20% of the load in the hot and humid southeast, but the entire load in the mountain west. The minimum storage capacity to meet the entire annual load decreased with decreasing LRR and decreasing Trad. For the southeast, large capacity was required, but for Louisville, for instance, sufficient capacity was provided by 0.05 m3 of water per m2 of floor area for LRR = 0.35 m/hr. These results demonstrate that for much of the US, sky radiation has the potential to serve the entire annual sensible and latent cooling load.
TOPICS: Radiation (Physics), Stress, Cooling, Storage, Temperature, Climate, Ventilation, Condensation, Flow (Dynamics), Thermal energy storage, Water, Meteorology
M. Adrienne Parsons and M. Keith Sharp
J. Sol. Energy Eng   doi: 10.1115/1.4042453
A heat pipe augmented sky radiator system was simulated by a thermal network, including a thin polyethylene cover with and without condensation, white (ZnO) painted radiator plate, condenser and evaporator ends of the heat pipe, thermal storage fluid (water), tank wall, room, sky and ambient air. Nodal temperatures were simultaneously solved as functions of time using Typical Meteorological Year (TMY3) weather data for Louisville, KY. Auxiliary cooling was added as needed to limit room temperature to a maximum of 23.9°C. Effects of radiator orientation, thermal storage capacity and cooling load to radiator area ratio, LRR. Results were compared to a baseline with LRR = 10 W/m2K, horizontal radiator and one cover, which provided an annual sky fraction (fraction of cooling load provided by sky radiation) of 0.855. A decrease to 0.852 was found for an increase in radiator slope to 20°, and a drop to 0.832 for 53° slope (latitude + 15°, a typical slope for solar heating). These drops were associated with increases in average radiator temperature by 0.73°C for 20° and 1.99°C for 53°. A 30% decrease in storage capacity decreased sky fraction to 0.843. Sky fractions were 0.720 and 0.959 for LRR of 20 and 5, respectively. LRR and thermal storage capacity had strong effects on performance. Radiator slope had a surprisingly small impact, considering that the view factor to the sky at 53° tilt is less than 0.5.
TOPICS: Cooling, Radiation (Physics), Temperature, Thermal energy storage, Stress, Heat pipes, Condensers (steam plant), Solar heating, Storage, Condensation, Fluids, Water, Meteorology
Sahil Arora, Geleta Fekadu and Sudhakar Subudhi
J. Sol. Energy Eng   doi: 10.1115/1.4042454
This present study aims to evaluate the performance of a solar flat-plate collector using Al2O3/water nanofluid and pure water. Experimental setup comprises of a special type of solar flat plate collector, a closed working fluid system and the measurement devices (thermocouples, temperature meter, flow meter and solar power meter). The absorber plate of the solar flat plate collector is made of two aluminum plates sandwiched together with Marquise-shaped flow channels. The effects of various parameters like collector inlet and outlet fluid temperature, mass flow rate of fluid, solar radiation, and ambient temperature on the energy and the exergy efficiency of the collector are investigated. The maximum energy efficiencies attained are 83.17% and 59.72%, whereas the maximum exergy efficiency obtained are 18.73% and 12.29% for the 20 nm- Al2O3/water nanofluids and pure water respectively at the mass flow rate of 3 liters per minute. The sophisticated design of absorber plate gives higher efficiency than that of conventional absorber plate.
TOPICS: Solar collectors, Exergy analysis, Flat plates, Nanofluids, Water, Solar energy, Flow (Dynamics), Temperature, Fluids, Exergy, Design, Solar radiation, Flowmeters, Aluminum plate, Solar power, Thermocouples
Smail Bendara, Sidi Mohammed El Amine Bekkouche, Tayeb Benouaz, Sabrina Belaid, Maamar Hamdani, Mohamed Kamal Cherier, Azzedine Boutelhig and Noceir Benamrane
J. Sol. Energy Eng   doi: 10.1115/1.4042455
Financial energetic problems incite citizens to focus on optimal energy consumption. Accordingly, the recent research showed that major financial economies can be optimally achieved, by introducing some passive measures. The main objective of the current contribution is to investigate the impact of thermal insulation and compactness on energy efficiency. Following the assessment of the methodology, several input parameters were identified and economic insulation thicknesses were obtained. Finding revealed that the best effectiveness of solar gain has been observed for a better insulation and a good compactness, whereas, a reduction of about 12.51 % of energy needs can be achieved. Similar to the previous case, compactness has an attractive effect, provided that the building was well insulated. Furthermore, any variance can't be occurred in economic insulation thickness by varying the building compactness. Unlike this remark, for a better compactness, a slight increase in the investment-return time has been noticed, following the energy bill reduction which becomes more interesting. Hence, the comparative study averred that the previous passive concepts provide a reduction of energy demand nearest 73.64 %. Thus, reduction was nexus 82.17 %, during cold season, and around 59.87 %, in overheating period. Following the obtained results, it can be concluded that the studied structure type may be integrated in the buildings within the energy label "type C".
TOPICS: Energy efficiency, Insulation, Thermal insulation, Solar energy, Energy consumption, Structures
Jana Möllenkamp, Mercedes H. Rittmann-Frank, Andreas Häberle, Thomas Beikircher and Wolfgang Schoelkopf
J. Sol. Energy Eng   doi: 10.1115/1.4042456
Process heat represents a major share of final energy consumption in the industrial sector and can partly be provided by solar thermal systems. To date, there has been little experience with solar heat plants for industrial processes operating at medium temperature level (100 - 250 °C). This paper focuses on the analysis of reduced solar gains by heating-up processes (capacitive thermal losses) in a parabolic trough collector field of 627m^2 aperture area providing solar heat for a Swiss dairy at 120 °C: Heating-up thermal masses is experimentally quantified by a new method using existing temperature sensors. The unused solar thermal gains of heating-up periods amount to 18% of possible useful solar gains in 2014. In winter months this share can reach 50 %. An intermediate storage or smaller heat capacities should be considered to reduce these losses. Also thermal losses of the piping system during full-operation are analysed. With properly installed insulation they are theoretically proven to be below 3% of useful solar gains. The analyses are based on the evaluation of highly time-resolved measurements of one year.
TOPICS: Pipes, Solar energy, Heat, Parabolic troughs, Heating, Solar heating, Storage, Temperature sensors, Temperature, Thermal systems, Energy consumption, Insulation, Piping systems
Ellen B. Stechel
J. Sol. Energy Eng   doi: 10.1115/1.4042417
Non applicable
TOPICS: Solar energy
Tatsuya Kodama
J. Sol. Energy Eng   doi: 10.1115/1.4042316
Essay for the JSEE special issue.
TOPICS: Solar energy, Chemistry, Hydrogen
Erik Koepf
J. Sol. Energy Eng   doi: 10.1115/1.4042282
This Editorial serves as an introduction to the ASME Journal of Solar Energy Engineering special issue on concentrated solar chemistry, fuels, and power.
TOPICS: Fuels, Solar chemistry, Solar energy
Viridiana G Morales Garza, Jonathon Sumner, Jörn Nathan and Christian Masson
J. Sol. Energy Eng   doi: 10.1115/1.4042242
This study uses the Reynolds-Averaged Navier-Stokes equations to validate a canopy model by computing a fully developed wind flow within and above a horizontally homogeneous dense forest as in the work of Dalpe and Masson. The model is paired with a modified k-e turbulence closure. A set of boundary conditions that rely on the law of the wall for a sustainable atmospheric boundary layer is used. All simulations are conducted in the open source software OpenFOAM v.2:4:0. Two practical aspects are considered in the validation process. First, an accurate leaf area index (LAI) integration to exactly fit the wind shear is evaluated. Since the physical foliage parameters may not be accessible for all type of forests, a generic leaf area density a distribution is tested. The results of this test show that a generic distribution is sufficient for preliminary analyses to improve accuracy of wind flow predictions over forested terrain. Second, the approach of Dalpe and Masson is limited to cyclic boundary conditions which are not practical for real sites. For cases without cyclic boundary conditions, imposing a proper slope on the inlet velocity profile is of high importance. This condition can be achieved through adjustment of the roughness length at the inlet.
TOPICS: Flow (Dynamics), Modeling, Model validation, Reynolds-averaged Navier–Stokes equations, Wind, Boundary-value problems, Computer software, Sustainability, Density, Turbulence, Wind shear, Simulation, Surface roughness, Navier-Stokes equations, Boundary layers, Engineering simulation

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