Voltage and Power Ratio Effects of Grid-Connected PV Plant's Operation on the Performance Ratio and Total System Efficiency

2006 ◽  
Author(s):  
R. Gonzalez ◽  
H. R. Jimenez ◽  
J. M. Huacuz
Keyword(s):  
Performance Ratio ◽  
Total System ◽  
Power Ratio ◽  
System Efficiency

scholarly journals Total System Performance Ratio—A Systems Based Approach for Evaluating HVAC System Efficiency

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5108
Author(s):  
Supriya Goel ◽  
Michael Rosenberg ◽  
Juan Gonzalez ◽  
Jérémy Lerond
Keyword(s):  
System Performance ◽  
Software Tool ◽  
The United States ◽  
Performance Ratio ◽  
System Evaluation ◽  
Total System ◽  
Hvac System ◽  
System Efficiency ◽  
Heating And Cooling ◽  
Code Structure

The prescriptive path is the most widely used approach for commercial code compliance in the United States. Though easy to implement, prescriptive approaches do not typically discriminate between minimally compliant, high-performing and poorly performing HVAC system configurations. Hence, to meet aggressive energy and carbon reduction goals, it is clear that energy codes will need to transition from prescriptive to performance-based approaches, a transition that is riddled with several challenges. This paper discusses a new HVAC system-based performance approach (HVAC System Performance) which provides a simpler solution to HVAV system evaluation compared to whole building performance, while keeping tradeoffs limited to specific building systems. The Total System Performance Ratio (TSPR) is a metric for evaluation of overall system efficiency instead of individual component efficiency, a solution which could also eventually facilitate the transition to a 100% performance-based code structure. TSPR is a ratio that compares the annual heating and cooling load of a building to the annual energy consumed by the building’s HVAC system. A calculation software tool has been developed for determining a building’s TSPR. Already incorporated into the 2018 Washington State Energy Code, this approach is also being evaluated by ASHRAE Standard 90.l Project Committee and has the potential to provide a comprehensive performance-based approach for HVAC system evaluation and analysis.

Soft Switching Approach to Reducing Transition Losses in an On/Off Hydraulic Valve

2009 ◽  
Author(s):  
Michael B. Rannow ◽  
Perry Y. Li
Keyword(s):  
Hydraulic System ◽  
Check Valve ◽  
Fluid Flows ◽  
Soft Switching ◽  
Total System ◽  
System Efficiency ◽  
Hydraulic Systems ◽  
Controlled Systems ◽  
Flow Through ◽  
Hydraulic Valve

A method for significantly reducing the losses associated with an on/off controlled hydraulic system is proposed. There has been a growing interest in the use of on/off valves to control hydraulic systems as a means of improving system efficiency. While on/off valves are efficient when they are fully open or fully closed, a significant amount of energy can be lost in throttling as the valve transitions between the two states. A soft switching approach is proposed as a method of eliminating the majority of these transition losses. The operating principle of soft switching is that fluid can temporarily flow through a check valve or into a small chamber while valve orifices are partially closed. The fluid can then flow out of the chamber once the valve has fully transitioned. Thus, fluid flows through the valve only when it is in its most efficient fully open state. A model of the system is derived and simulated, with results indicating that the soft switching approach can reduce transition and compressibility losses by 79%, and total system losses by 66%. Design equations are also derived. The soft switching approach has the potential to improve the efficiency of on/off controlled systems and is particularly important as switching frequencies are increased. The soft switching approach will also facilitate the use of slower on/off valves for effective on/off control; in simulation, a valve with soft switching matched the efficiency an on/off valve that was 5 times faster.

scholarly journals Performance Evaluation of 100kWp Roof-top Grid-connected PV System installed in Northern India

2019 ◽  
Vol 8 (3) ◽  
pp. 8441-8444 ◽  
Keyword(s):  
Degradation Rate ◽  
Capacity Utilization ◽  
Plant Performance ◽  
Performance Ratio ◽  
Energy Output ◽  
System Efficiency ◽  
Pv System ◽  
Utilization Factor ◽  
Northern India ◽  
Efficiency Performance

The performance of 100 kWp roof-top grid-connected PV system was evaluated. The plant was installed at PGDM building in Sharda University, Greater Noida in northern India. The plant was monitored from March 2018 to February 2019. Performance parameters such as system efficiency, performance ratio, capacity utilization factor, and degradation rate were obtained. The plant performance result was compared with the estimated results obtained from SAM and PVsyst software. The total annual energy output was found to be 16426 kWh. The annual average system efficiency and capacity utilization factor of the plant was found to be 15.62 % and 14.72 % respectively. The annual performance ratio and annual degradation rate were found to be 76% and 1.28%/year respectively. The annual performance ratio obtained from SAM and PVsyst was found to be 78% and 82% respectively. It was noticed that the measured performance ratio was highly relative with the one obtained from SAM software.

Soft Switching Approach to Reducing Transition Losses in an On/Off Hydraulic Valve

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Michael B. Rannow ◽  
Perry Y. Li
Keyword(s):  
Hydraulic System ◽  
Check Valve ◽  
Fluid Flows ◽  
Soft Switching ◽  
Total System ◽  
System Efficiency ◽  
Hydraulic Systems ◽  
Controlled Systems ◽  
Flow Through ◽  
Hydraulic Valve

A method for significantly reducing the losses associated with an on/off controlled hydraulic system is proposed. There has been a growing interest in the use of on/off valves to control hydraulic systems as a means of improving system efficiency. While on/off valves are efficient when they are fully open or fully closed, a significant amount of energy can be lost in throttling as the valve transitions between the two states when the switching times are not negligible. A soft switching approach is proposed as a method of eliminating the majority of these transition losses. The operating principle of soft switching is that fluid can temporarily flow through a check valve or into a small chamber while valve orifices are partially closed. The fluid can then flow out of the chamber once the valve has fully transitioned. Thus, fluid flows through the valve only when it is in its most efficient fully open state. A model of the system is derived and simulated, with results indicating that the soft switching approach can reduce transition and compressibility losses by 81% and total system losses by 64%. The soft switching approach has the potential to improve the efficiency of on/off controlled systems and is particularly beneficial as switching frequencies are increased. The soft switching approach will also facilitate the use of slower on/off valves for effective on/off control; in simulation, a valve with soft switching matched the efficiency of an on/off valve that was 4.4 times faster.

Investigation of Accumulator Parameters for a Novel Hybrid Architecture

2020 ◽  
Vol 32 (5) ◽  
pp. 876-884
Author(s):  
Seiji Hijikata ◽  
Kazuhisa Ito ◽  
Hubertus Murrenhoff ◽  
◽  
Keyword(s):  
Hybrid System ◽  
Energy Savings ◽  
Combustion Engine ◽  
Pressure Level ◽  
Operating Costs ◽  
Hybrid Architecture ◽  
Total System ◽  
System Efficiency ◽  
Pressure System ◽  
Gas Volume

An open center system (OC-System), which is one of the major hydraulic architectures for excavators, has been improved in the world to reduce fuel consumption for global environment conservation and lower operating costs. However, the total system efficiency, including the internal combustion engine (ICE), has not been thoroughly considered. In contrast, a constant pressure system (CP-System) enabling the engine to be driven optimally is developed, but is not accepted in the industry owing to the complexity of the required components. Thus, in this research, a hybrid system combining an OC-System with a CP-System is proposed to improve the total system efficiency. An accumulator, which is used to provide flow rate to actuators, is essential for the new hybrid system, and it is vital to consider the nominal gas volume and pressure level for the accumulator in terms of energy savings and initial cost. Therefore, the influences of accumulator volume and pressure level are discussed in this paper.

Simulation of Utilisation of Pressure Propagation for Increased Efficiency of Secondary Controlled Discrete Displacement Cylinders

2012 ◽  
Vol 233 ◽  
pp. 3-6 ◽  
Author(s):  
Rico H. Hansen ◽  
Anders Hansen ◽  
Torben O. Andersen
Keyword(s):  
Power Systems ◽  
Energy Efficient ◽  
Discrete Control ◽  
Total System ◽  
System Efficiency ◽  
Discrete Variation ◽  
Minimum Loss ◽  
Fluid Power Systems ◽  
Fixed System ◽  
Pressure Propagation

A key component of upcoming secondary controlled fluid-power systems for e.g. wave energy is the implementation of discrete force control of cylinders by discrete variation of the cylinder displacement. However, as the discrete control is implemented by shifting between fixed system pressures in multiple cylinder chambers using on/off valves, the energy efficiency of the performed shifts is essential for the total system efficiency. However, pressure shifting on a volume, where the dynamics of pressure propagation in the pipelines is negligible have been proved to have an unavoidable minimum loss due to the compressibility of the fluid. This paper performs a simulation study, showing that an improved energy efficient shift may be implemented by utilising the pressure propagation in the line between valve and cylinder chamber.

scholarly journals Fuel Utilization Effects on System Efficiency and Solid Oxide Fuel Cell Performance in Gas Turbine Hybrid Systems

2017 ◽  
Author(s):  
Nor Farida Harun ◽  
Lawrence Shadle ◽  
Danylo Oryshchyn ◽  
David Tucker
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Hybrid Systems ◽  
Cell Length ◽  
Inlet Temperature ◽  
Total Efficiency ◽  
Total System ◽  
System Efficiency ◽  
Fuel Utilization ◽  
Fuel Cell Performance

The simulation work presented herein characterizes the performance of a recuperated gas turbine (GT) hybrid systems in response to different levels of fuel utilization (Uf) by the SOFC. The SOFC performance was compared with and without anode recycle (AR), operating at 90% total stack Uf (Uf.stack). A study at 65% Uf was also considered as a reference case for the hybrid power system without anode recycle, i.e. using single-pass cell fuel utilization (Uf.cell). All three cases in this paper were evaluated at design points for a 550 MW hybrid system using coal-derived syngas feed with zero methane. A previously developed one-dimensional (1D) fuel cell model was used to simulate the distributed profile of thermal and electrochemical properties along the fuel cell length. Fuel cell total current density, average solid temperature, and cathode inlet temperature were maintained identical at each fuel utilization to avoid confounding the results with the impacts of SOFC degradation. The maximum system efficiency of 71.1% was achieved by SOFC/GT non-recycle systems at 90% Uf.cell (with 90% Uf.stack). The case at 65% Uf.cell (with 65% Uf.stack) demonstrated 70.7% total efficiency, only 0.4% point lower than at 90% Uf.cell. However, integrating anode recycle to the system significantly reduced the maximum total efficiency to 55.5%. Although the distributed SOFC performance across the cell length for 65% Uf.cell with AR at 90% Uf.stack was similar to the 65% Uf.cell (with 65% Uf.stack), recycling anode off-gas resulted in lower fuel cell Nernst potential that caused further drop in both stack and total system efficiency.

Multi Effects Desalination-Mechanical Vapor Compression Powered by Low Temperature Supercritical Organic Rankine Cycle

2017 ◽  
Author(s):  
Eydhah Almatrafi ◽  
Francesca Moloney ◽  
D. Y. Goswami
Keyword(s):  
Power Consumption ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Performance Ratio ◽  
Specific Power ◽  
Working Fluid ◽  
Low Grade ◽  
Vapor Compression ◽  
System Efficiency ◽  
Specific Power Consumption

Availability of clean drinking water and power are two important issues in the world. In this paper, an innovative new design of multi effect desalination coupled with mechanical vapor compression (MED-MVC) powered by supercritical organic Rankine cycle utilizing a low grade solar heat source using evacuated tube collectors is analyzed. The supercritical organic Rankine cycle efficiency is about 10% at 150°C and 5MPa with R152a as the working fluid. The performance of the LT-MED-MVC was found to be better than similar systems found in the literature. The specific power consumption for MVC is lower than 1 kWh/m3 for seawater feed salinity of 42,000 ppm, 14 forward feed effects, and a recovery rate of 50%. The overall system efficiency is 7%. The impact of increasing the number of effects on the performance ratio, effect specific area, specific power consumption, solar collector area, and the system efficiency are also analyzed in this paper.

scholarly journals Integrating Solar Photovoltaics in Residential Buildings: Towards Zero Energy Buildings in Hail City, KSA

2021 ◽  
Vol 13 (4) ◽  
pp. 1845
Author(s):  
Mohamed Hssan Hassan Abdelhafez ◽  
Mabrouk Touahmia ◽  
Emad Noaime ◽  
Ghazy Abdullah Albaqawy ◽  
Khaled Elkhayat ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Co2 Emissions ◽  
Tilt Angle ◽  
Residential Buildings ◽  
Performance Ratio ◽  
Energy Sources ◽  
System Efficiency ◽  
Zero Energy ◽  
Pv System ◽  
Pv Module

In recent years, most cities have faced great demand for electricity supply due to rapid population growth and industrialization. Supplying sufficient electrical energy, while reducing greenhouse gas emissions, is one of the major concerns of policymakers and scientists all over the world. In Saudi Arabia, local authorities are increasingly aware of the necessity of reducing the environmental impact of nonrenewable energy by exploring alternative sustainable energy sources and improving buildings’ energy efficiency. Recently, building-integrated photovoltaic (BIPV) technology has been regarded as a promising technology for generating instantaneous sustainable energy for buildings. To achieve a substantial contribution regarding zero energy buildings, solar energy should be widely used in residential buildings within the urban context. This paper examines how to achieve an appropriate model for integrating photovoltaics on the rooftop of residential buildings in Hail city to provide alternative energy sources. The estimated rooftop areas in Hail city, utilizable for PV application were calculated. Using PV*SOL simulation software, the performance ratio and the system efficiency, as well as the annual energy output in several tilt angles, were determined and presented. The amount of energy expected when using all effective roof area in the city was also calculated. The amount of CO2 emissions that could be reduced as a result of using a PV system was estimated. The results show a significant area of rooftop suitable for PV system in residential buildings in Hail city, which exceeds 9 million square meters. On the other hand, the performance ratio and the system efficiency are affected by the tilt angle of the PV module, where the efficiency increases with higher tilt angle, this is due to the PV module temperature, where, with the decrease in the PV module temperature its efficiency increases. The results indicate that the 30° tilt PV produced the highest amount of energy, whereas the 75° tilt PV records the smallest one although it achieves the best possible efficiency. There is a significant amount of energy produced from the use of all residential rooftops in Hail, and there is also a significant reduction in the amount of CO2 emissions. It is expected that this research would develop innovative building design strategies and specifications allowing for better climate and energy efficiency as well.

scholarly journals Thermodynamic analysis of air refrigerator on exergy graph

2006 ◽  
Vol 10 (1) ◽  
pp. 99-110 ◽  
Author(s):  
Vladimir Nikulshin ◽  
Margaret Bailey ◽  
Viktoria Nikulshina
Keyword(s):  
Thermodynamic Analysis ◽  
Exergy Efficiency ◽  
Total System ◽  
Individual Element ◽  
System Efficiency ◽  
Innovative Method ◽  
Loss Models ◽  
The Relationship ◽  
Exergy Losses ◽  
Intensive System

Improving mechanical system efficiency is the goal of many engineers and scientists. Commonly, the solutions to these types of problems are uncovered using thermodynamic analysis and optimization. An innovative method for the thermodynamic analysis of a complex energy-intensive system with an arbitrary structure is described in this paper. The method is based on a novel general equation to calculate the total system exergy efficiency using an exergy flow graph proposed by the authors. Discuss in this paper exergy efficiency and exergy loss models as well this approach allows a user to obtain not only the exergy losses and efficiency of the total system, but also to show the relationship between the exergy efficiency of an individual element and that of the entire system. An example is provided that employs this method to the thermodynamic analysis of an air refrigerator.

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