Suresh B. Sadineni

A Photo‐neutron Source for a Sub‐Critical Nuclear Reactor Program

Experiments to benchmark photo‐neutron production calculations for an Accelerator Driven Sub‐Critical System (ADS) are described. A photo‐nuclear based neutron source with output > 1013 n/sec has been proposed as a driver for a program using the sub‐critical assembly at Idaho State University. The program is intended to study ADS control issues arising from coupling an accelerator neutron source with a sub‐critical assembly. The experiments were performed using the 20 MeV electron linear accelerator at the Idaho Accelerator Center (IAC). Results of calculations, that were made using ACCEPT, PINP, MCNP, and MCNPX codes to optimize photo‐nuclear based neutron conversion targets, are compared to experimental data for a single energy measurement.

A Cost Effective Solar Tracker and Performance Monitoring System for Utility Scale Photovoltaic Installations

A prototype of an integrated tracking and monitoring system is developed and experimentally tested in the environmental conditions of the desert south-west. This system hardware design incorporates both the tracker control and performance monitoring mechanism. A wireless communication protocol coupled with internet transmits the PV panel performance information collected by the electronic sensors to a remote user who can monitor the system performance. The initial experimental results of this newly developed system performance are presented. Finally, an economic analysis is conducted to evaluate the applicability of the current system to a utility scale installation.The preliminary results suggest that there would be a 25% average increase in solar insolation received by a single-axis tracking surface over a fixed (tilt equal to local latitude) surface during the winter months. Although, limited amount of data is available for typical summer days, results from September days suggest an increase in solar insolation as high as 38%. Also, such an integrated tracking and monitoring system will yield in better monitoring resolution due to monitoring at the string level as opposed to central inverter level in the central inverter type PV power plant topology.The monitoring sub-system design incorporates cutting edge electronic sensors. The measurements using these sensors were compared against the measurement through a programmable D.C load. The difference between both the power measurements is well within a median of 5–12% suggesting a good agreement between both the measurements.Copyright

An Integrated Performance Monitoring and Solar Tracking System for Utility Scale PV Plants

Monitoring of photovoltaic (PV) systems is essential for achieving reliable and, maximum yield from solar PV plants. This paper proposes PV plant hierarchy, and a novel near real-time monitoring system combined with a solar tracking controller for utility scale PV installations. Currently, most PV installations employ monitoring at the inverter level, lacking sufficient resolution. Furthermore, the solar tracking and performance monitoring systems are isolated from one another. The proposed design increases monitoring resolution, allowing PV malfunctions to be addressed immediately, effectively optimizing a plant’s power generation. Moreover, the tracker control and monitoring are fused into an inclusive hardware design. Incorporating state-of-the-art electronic sensors, coupled with wireless communication protocols, the resulting system is a robust, accurate sensor and control network. Accessible through the internet, the system will provide a way to monitor and control multiple installations from a centralized location. The collected data enables efficient maintenance scheduling, and long-term performance analysis for utility scale PV plants. The developed system includes string level power measurement sensors, sun tracking actuators, a network of microprocessors and a central processing unit (CPU) for application in utility-scale central inverter PV plants. The basic designs and feasibility of the system are presented in this paper.© 2011 ASME

Experimental Comparison and Economic Analysis of PV Technologies for Utility Scale Installations

The photovoltaic (PV) industry has seen remarkable progress in recent years, especially considering the advancement in materials and cell architecture. The potential of these technologies is investigated in a high insolation region of Southwestern United States, namely Las Vegas, where there is an abundance of surrounding barren land available for large scale installations. An experimental comparison of different PV technologies (HIT-Si, poly-c-Si, a-Si, and triple junction a-Si) under identical climatic conditions is the basis of this study. All tested modules have identical operating conditions, i.e. fixed installation plane, geographic location, and climatic conditions. The experiment verifies thin-film’s temperature independency, HIT-Si’s superior performance, and summarizes winter energy production of popular technologies in our climate. Lastly, an economic analysis is performed to compare the different technologies for prospective utility scale PV installations in southern Nevada, or similar climatic regions.Copyright

Development of a Façade Evaluation Facility for Experimental Study of Building Energy

The goal of the project is to evaluate various types of facades’ behavior and effects on building energy, focused primarily on building fenestrations such as windows. Development of the facade evaluation facility and requirements are presented in this paper. The test facility is a complete standalone unit designed to replicate a section of a building. Accommodation for facilitating a wide range of fenestrations was an important criterion. An effective solution was developed that allowed instant interchangeability of the facade setup. Although, due south orientated facades was of primary interest, integration of a rotating carousel base allowed flexibility in adjusting the orientation of the test facility. Experimental procedures and instrumentation layout are discussed in detail. The temperature of the indoor environment is continuously controlled and monitored. The measured fenestration characteristics include thermal and optical properties of the windows. The test results reveal the fenestration performance. The outcome of these tests enumerates the effects of the facade on the overall heating and cooling loads of buildings. Further investigation into these characteristics assists in improving building energy efficiency. Due to the versatility of the facility, quick replacement of the facade can accommodate several tests in short durations of time. Furthermore, correlation of the results can be scaled appropriately for residential or commercial settings providing practical information for wide utilization, contingent upon the window type.Copyright

Optimization of a Coupled Vapor Compression and Absorption Cooling System Driven by Gas Fueled IC Engine

In recent years, due to the increased fossil fuel costs and environmental concerns, there has been a renewed interest in absorption cooling (using low-grade heat source) systems for refrigeration and space cooling applications. Although, the stand-alone coefficient of performance (COP) is a concern with such systems, absorption cooling can be a useful add-on that improves the overall efficiency of conventional vapor compression cooling cycle. A local company based in Las Vegas which is involved in the development of advanced HVAC technologies, has developed a natural gas fueled internal combustion (IC) engine driven heat pump. This system recovers the rejected heat from the IC engine during the heating cycle, thus, increasing the heat delivered and improving the system’s overall efficiency. However, during the cooling cycle the rejected heat is dissipated to the ambient air through radiators. The overall efficiency of the system can be improved if the heat rejected during the cooling cycle can be recovered and used for space cooling or refrigeration applications. In this study, a vapor compression refrigeration system coupled with an absorption cooling system is simulated using MATLAB. The vapor compression system is driven by a natural gas fueled IC engine and the waste heat from the engine is used to drive the absorption cooling system. The waste heat is recovered both from gas exhaust and engine cooling systems. The developed simulation model is used to find the transients of both the vapor absorption and compressions systems for varied cooling demands. Important parameters such as coolant temperature and exhaust gas temperature are obtained from experimental data. This paper presents the most efficient load distribution between the vapor compression and absorption cooling systems.Copyright

Solar Assisted Desiccant Cooling Simulation for Different Climate Zones

Evaporative cooling is among the most cost effective methods of air conditioning, but is less efficient in humid climates. An evaporative system coupled with a desiccant wheel can operate effectively in broader climatic conditions. These cooling systems can substitute traditional vapor compression air conditioning systems as they involve environmentally friendly cooling processes with reduced electricity demand (which is commonly generated from fossil fuels) along with no harmful CFC based refrigerant usage. Furthermore, direct utilization of low grade energy sources such as solar thermal energy or flue gas heat can drive the desiccant regeneration process, thus providing economic benefits. This study presents the results of simulations of desiccant cooling system performance for different climate zones of the United States. Solar assisted desiccant air conditioning is particularly useful where there are abundant solar resources with high temperature and humidity levels. Building energy simulations determined cooling energy requirements for the building. Simulation of an evacuated solar hot water collector model provided the heat energy available for regeneration of the desiccant. Solid desiccant of common material such as silica gel used in a rotary wheel is simulated using established validated computer models; this is coupled with evaporative cooling. Transients of the overall system for different cooling loads and solar radiation levels are presented. Finally, feasibility studies of the desiccant cooling systems are presented in comparison with traditional cooling system. Further analysis of the data presents optimization opportunities. Energy savings were achieved in all climatic conditions with decreased effectiveness in more humid conditions.Copyright

Measurements and Simulations of Electrical Demand From Residential Buildings for Peak Load Reduction

Due to extreme summers in the Desert Southwest region of the U.S., there are substantial peaks in electricity demand. Through a grant from the U.S. Department of Energy, a consortium has been formed between the University of Nevada Las Vegas, Pulte Homes, and NV Energy (formerly known as Nevada Power) to address this issue. The team has been developing a series of approximately 200 homes in Las Vegas to study substation level peak electric load reduction strategies. The targeted goal of the project is a peak reduction of more than 65%, between 1:00 PM and 7:00 PM, compared to code standard housing developments. Energy performances of the homes have been monitored and the results were stored for further analysis. A computer model has been developed for one of the homes in the new development using building energy simulation code, ENERGY 10. Influence of different peak reduction strategies on the electricity demand from the home has been analyzed using the developed model. The simulations predict that the annual electrical energy demand from the energy efficient home compared to a code standard home of the same size decreases by 38%. The simulations have also shown that the energy efficient measures reduce the electricity demand from the home during the peak periods. Simulations on the photovoltaic (PV) orientation show that a south oriented PV system is best suited for a home enrolled to flat electricity pricing schedule and a 220°(40° west of due south) orientation is economically optimal for homes enrolled in the time-of-use pricing. The energy efficiency methods in the building coupled with a 220° oriented PV and two degrees thermostat setback for three hours (from 3:00–6:00 PM) can reduce the peak demand by 62% compared to a code standard building of the same size.Copyright

Home Energy Conservation in the Las Vegas Valley

Pulte Homes, a production home builder and community developer partnering with the U.S. Department of Energy’s Building America program, has collaborated with the Center for Energy Research at the University of Nevada, Las Vegas, and NV Energy, the local electric utility, on an energy conservation project in the Las Vegas Valley. This study entails four model homes at a new development named Villa Trieste, located in the Summerlin community of Las Vegas. The models, ranging in floor plan area from 1,487 to 1,777 square feet, have been constructed under the Environments for Living program and have been platinum certified by LEED (Leadership in Energy and Environmental Design) for Homes. According to the Home Energy Rating System Index, all four models are over 50% more efficient than homes of equal size built to 2006 International Energy Conservation Code standards. The study focuses on the cost benefit of installing additional efficiency upgrades in future homes at the development. Though all proposed upgrades offer reductions in energy use, many offer little improvement relative to their installation costs. Higher-efficiency windows, heat recovery ventilators, and R-36 spray foam attic insulation have been deemed appropriate measures for future homes. All homes are to be equipped with photovoltaic arrays; increasing the size of the arrays will cost-effectively reduce net energy consumption.Copyright

Reclaiming Electrolysis Reject Water With a Solar Still

Electrolysis is one sustainable pathway to hydrogen production. During this process, however, it is common to reject a large portion of the water during the pretreatment process to carry away impurities. We have been examining water-conserving approaches to this problem with low energy devices. One such approach is to couple the water purification step with a solar still, thus allowing some of the wastewater to be recycled and utilized in the hydrogen production. This paper reports on a study of a weir type solar still. A weir type solar still is an inclined solar still with the absorber plate formed to make weirs, as well as a top basin and a bottom basin. Raw water flows from the top basin through the weirs and to the bottom basin that is circulated back to the top basin by a small pump. Purified water is collected from condensate on the glass cover. The weir type solar still with 0.61 m width and 1.82 m length (net aperture area 0.97 m2 ) was constructed and tested for the Las Vegas weather conditions. A data acquisition system with temperature and flow rate sensors was also installed to record the transient variation of temperature and flow rate. The distillate productivity of the still with double-pane and single-pane glass covers is compared. The average distillate productivities for double-pane and single-pane glass covers were approximately 1.9 l/m2/day and 5.5 l/m2/day in the months of August and September in Las Vegas respectively. A double-pane glass reduced the productivity of a solar still significantly due to the reduced temperature difference between the raw water and the glass inner surface. The productivity of the weir type still is also compared with the basin type still tested at the same location side by side and is found that the weir type still productivity was approximately 20% higher. The quality of distillate from the still was also analyzed to verify the product will meet the purity required by electrolyzers.Copyright