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Select this Article		Hybrid Train Power with Diesel Locomotive and Slug Car Based Flywheels, for NOx and Fuel Reduction Zhiyang Wang, Professor, Alan Palazzolo, and Junyoung Park Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000081 Posted ahead of print 11 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract An energy storage flywheel consists of a large inertia wheel sharing a common shaft with a motor generator set and with magnetic bearings to support the entire rotating assembly. Flywheels mounted on a special slug car are charged from the local utility grid and from regenerative braking events. Usage of these power sources reduces fuel consumption and the related NOx emission by the locomotive mounted, Diesel generator sets (DGS). The flywheel supplied power can replace the DGS supplied power in one or more of the 8 fixed power settings, (notches) plus idle and reverse, which are common to most locomotives either for line haul or switchyard service. The slug cars have separate traction motors to be driven by the flywheel systems so that the flywheel power and DGS power are electrically and physically decoupled. A system model is presented which includes the train dynamics coupled with the electromechanical models for the flywheels and traction motors. The modified Davis equation is employed in the train model to account for windage and other losses. A novel, feedback based flux weakening control of the flywheel's motor generator current‐torque and speed‐back EMF (Electro‐Motive Force) gain is employed to increase the charge capacity, depth of discharge and regenerative braking efficiency for the flywheels. The simulation results show significant cost and emissions reduction potential for the proposed hybrid DGS — flywheel locomotive power system in line haul and switcher service.

Select this Article		Prediction of Hourly Solar Radiation in Six Provinces in Turkey by Artificial Neural Networks Ozgur Solmaz and Muammer Ozgoren Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000080 Posted ahead of print 28 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract The aim of this study is to apply the method of the artificial neural networks (ANNs) to predict the hourly solar radiation of six selected provinces in Turkey. Six neurons receiving input signals of latitude, longitude, altitude, day of the year, and hour of the day and the mean of hourly atmospheric air temperature were used in the input layer of the network. One neuron producing a corresponding output signal of the hourly solar radiation was utilized in the output layer of the network. Two different models (Model I and Model II) have been analyzed in the formed ANNs for training and testing. The results obtained from both models were compared by using different neurons, mean squared error (MSE), coefficient of determination (R²), and mean absolute error (MAE). According to the results, MSE value of training data in Model II was better than Model I.

Select this Article		Unified Approach to Balanced Pricing Strategies for Backup Reserve and Wheeling in Power Systems M. A. El‐Kady, Y. A. Alturki, and F. M. Al‐Duaij Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000079 Posted ahead of print 20 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract This paper shares the results of a recent industry‐supported study with the aim to develop a practical pricing model for backup reserve and wheeling in the semi‐open market structure of power systems. Instead of a closed‐loop optimization framework, a key requirement in the study is to develop a systematic “what‐if” tableau‐type analysis with full control over pricing parameters during negotiations among market entities. With the help of newly developed compact and elegant universal distribution factors, the pricing framework attains a balanced strategy that ensures perceived benefits to both the buyer and the seller. The model and the associated computerized algorithm deal collectively with diverse issues, including: 1) fulfilling local firm real (and reactive) power demand requirements, 2) fulfilling local power reserve requirements, 3) buying firm real (and reactive) power from the grid, 4) buying reserve power from the grid, 5) exporting firm real (and reactive) power demand to remote load centers via the grid, 6) exporting reserve power via the grid, 7) wheeling of firm power demand to remote owned sites using the grid, and 8) wheeling reserve power to remote owned sites using grid. Practical implementation features of the computerized algorithms are also discussed with an illustrative case example.

Select this Article		Design and Performance Study of a Solid Oxide Fuel Cell and Gas Turbine Hybrid System Applied in Combined Cooling Heating and Power System Hsiao‐Wei D. Chiang, Chih‐Neng Hsu, Wu‐Bin Huang, Chien‐Hsiung Lee, Wei‐Ping Huang, and Wen‐Tang Hong Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000078 Posted ahead of print 17 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract High efficiency and very low emissions, fuel cells have been one of the choices of research in current energy development. The Solid Oxide Fuel Cell (SOFC) is a high temperature type fuel cell. It has the characteristic of very high operating temperature 1,027°C (1,300K). The SOFC has the main advantage of very high performance efficiency (over 50%), but also has very high exhaust temperature. Current studies point out that the combination of SOFC and Gas Turbine (GT) can produce efficiency more than 60%. The exhaust temperature of this hybrid power system can be as high as 227 – 327°C (500 – 600K). With this waste heat utilized, we can further improve the overall efficiency of the system. A simulation program of SOFC/GT system and the introduction of the concept of Combined Cooling, Heating, and Power System (CCHP) have been used in this study. The waste heat of SOFC/GT hybrid power generation system was used as the heat source to drive an Absorption Refrigeration System (ARS) for cooling. This waste heat enables the SOFC/GT to generate electricity in the system while providing additional cooling and heating capacity. Therefore, we have a combined CCHP system developed using three major modules which are SOFC, GT, and ARS modules. The SOFC module was verified by our test data. The GT and SOFC/GT modules were compared to a commercial code and literature data. Both the single‐ and double‐ effect ARS modules were verified with available literature results. Finally, the CCHP analysis simulation system, which combines SOFC, GT, and ARS, has been completed. With this CCHP configuration system, the fuel usability of the system by our definition could be above 100%, especially for the double effect ARS. This analysis system has demonstrated to be a useful tool for future CCHP designs with SOFC/GT systems.

Select this Article		Review of Water Use in U.S. Thermoelectric Power Plants Lamya Badr, Gregory Boardman, F. ASCE, and John Bigger Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000076 Posted ahead of print 10 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract The importance of water use in thermoelectric power plants is ever increasing across the nation. For example, power plants in New York and California are forced to deal with cooling systems that pose threats to ecosystems and water availability. The purpose of this paper is to summarize, compare, and contrast previous studies in this subject area using journal articles and government/laboratory reports. This literature review presents a myriad of results obtained from previously conducted research pertaining to: 1. Power generation in the U.S., 2. Water use in power plants, 3. Power plant cooling technologies, 4. Comparisons of cooling technologies (including cost), 5. Impact of drought on power generation, and 6. Projections of power generation and water use. Among the findings of this study was that while water usage data for once‐through and wet‐recirculating cooling systems are well‐developed, dry and hybrid cooling system data are not as complete. This review, therefore, serves as an assimilation of existing information and points out gaps in our knowledge base of the systems.

Select this Article		Novel Theoretical Approach on Exergy and Energy Performance Assessment of Cylindrical Solar Water Heater Alireza Rasekh and Mahmood Farzaneh‐Gord Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000075 Posted ahead of print 3 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, a novel theoretical analysis is carried out for evaluating the thermal performance, exergy efficiency as well as energy efficiency for a typical cylindrical solar water heater under given operating conditions. In this detailed mathematical modeling, a cylindrical coil tube in the shape of spiral rings, serves as a collector to the incident solar energy on the cylinder wall. The energy balance equations for both the fluid and tube have been established separately. The physical parameters which govern the system are identified. The governing differential equations have been solved for various values of the parameters. As it is difficult to determine these parameters through experiments, the non‐dimensional theoretical approach has been applied in this research. Finally, the influences of these parameters on exergy and energy efficiency, which are most significant factors in design of a cylindrical solar water heater, are investigated. The results of this theoretical analysis are in good agreement with the experimental measurements noted in the previous literature. The energy efficiency and exergy efficiency of the heater will be above 50% and 2%, respectively after optimizing the key parameters.

Select this Article		Evaluation of Optimization Algorithms to Adjust Efficiency Curves for Hydroelectric Generating Units Ieda G. Hidalgo, Darrell G. Fontane, M. ASCE, Mazdak Arabi, João E. G. Lopes, José G. P. Andrade, and Lubienska C. L. J. Ribeiro Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000074 Posted ahead of print 1 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract The power generated by a hydroelectric plant depends on the penstock head loss, the turbine efficiency and the generator efficiency; among other factors. Initially, the functions related to these variables are provided by the equipment manufacturer; however, over time they change as the plant ages. This paper presents a methodology to adjust an efficiency function for each generating unit based on measured data. It is applied using two optimization methods: the Generalized Reduced Gradient and the Evolutionary Algorithm. A case study with data from a large Brazilian hydroelectric plant demonstrates how the methodology can be employed and compares the performance of the optimization tools. A comparison metric is used to show that the optimal unit efficiency function significantly improves the performance of simulation models to reproduce observed data and better describe the actual operation of the hydroelectric plant.

Select this Article		Critical Submergence for Dual Rectangular Intakes Nevzat Yıldırım, Abdul Samet Eyüpoğlu, and Kerem Taştan Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000073 Posted ahead of print 1 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract The critical submergence for dual rectangular intakes with no partition walls was investigated. To predict this critical submergence, the same principles as the available superposition methods developed for multiple pipe intakes were followed. Experiments were conducted on dual rectangular intakes located in different relative positions in an incoming developed canal flow. Multiple (dual) intakes introduce “flow blockages” on one another's flow. A “flow blockage” is a kind of extra outflow (intake flow) for sink surfaces in addition to the flow of the intake. Due to such an additional suction flow, it is as if the discharge of the intake is increased. Because dual intakes introduce mutual flow blockages and cause more disturbances, the critical submergence is increased. The agreement between the theoretical and experimental results was found to be satisfactory. Depending on the flow and geometrical conditions, the correlation coefficients between the experimental and theoretical results vary 0.61 to 0.90.

Select this Article		Optimal Planning and Operation of Smart Grids with Electric Vehicle Interconnection M. Stadler, C. Marnay, M. Kloess, G. Cardoso, G. Mendes, A. Siddiqui, R. Sharma, O. Mégel, and J. Lai Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000070 Posted ahead of print 18 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Connection of electric storage technologies to smart grids will have substantial implications for building energy systems. Local storage will enable demand response. When connected to buildings, mobile storage devices such as electric vehicles (EVs) are in competition with conventional stationary sources at the building. EVs can change the financial as well as environmental attractiveness of on‐site generation (e.g. PV or fuel cells). In order to examine the impact of EVs on building energy costs and CO₂ emissions, a distributed‐energy‐resources adoption problem is formulated as a mixed‐integer linear program with minimization of annual building energy costs or CO₂ emissions and solved for 2020 technology assumptions. The mixed‐integer linear program is applied to a set of 139 different commercial buildings in California and example results as well as the aggregated economic and environmental benefits are reported. Special constraints for the available PV, solar thermal, and EV parking lots at the commercial buildings are considered. The research shows that EV batteries can be used to reduce utility‐related energy costs at the smart grid or commercial building due to arbitrage of energy between buildings with different tariffs. However, putting more emphasis on CO₂ emissions makes stationary storage more attractive and stationary storage capacities increase while the attractiveness of EVs decreases. The limited availability of EVs at the commercial building decreases the attractiveness of EVs and if PV is chosen by the optimization, then it is mostly used to charge the stationary storage at the commercial building and not the EVs connected to the building.

Select this Article		Fast MPC‐Based Coordination of Wind Power and Battery Energy Storage Systems Le Xie, Yingzhong Gu, Ali Eskandari, and Mehrdad Ehsani Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000071 Posted ahead of print 4 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract In this paper we present a model predictive control (MPC)‐based coordinated scheduling framework for variable wind generation and battery energy storage systems (BESS). Based on short‐term forecast of available wind generation and price information, a joint look‐ahead optimization is performed by the wind farm and storage system to determine their net power injection to the electric power grid. In conjunction with moderate battery capacity, the excess unpredictable wind generation can be used to charge the battery storage and vice versa. The benefits of the proposed scheduling approach are that (1) the combined profit of wind generation and BESS is increased, (2) the net power injection from the wind farm into the power grid is smoothed out, and (3) the look‐ahead optimization updates the price prediction in a moving horizon, which leads to more robust profit for wind farm and BESS against price uncertainties. By formulating the MPC‐based coordinated scheduling as a quadratic programming problem, we propose several numerically efficient algorithms to compute the optimal control strategy for wind generation and BESS. We demonstrate the effectiveness of the proposed algorithm in a modified IEEE 24‐bus Reliability Test System with aggregated PHEVs. It is shown that the proposed algorithm can increase the joint profit of wind farm and BESS while smoothing out the net power injection to the electricity grid. The proposed MPC‐based scheduling problem can be solved in about 400 milliseconds, which makes the framework implementable in real time electricity market operations.

Select this Article		Ex‐Ante Assessment of the Implementation of an Energy Efficiency Certificate Scheme in Chile Juan G. Norero and Enzo E. Sauma Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000068 Posted ahead of print 19 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract Energy efficiency (EE) policies are mostly implemented in developed countries. However, the benefits of their implementation in developing countries may be quite large. In this article, we study the potential implementation of an EE certificates scheme in Chile. In particular, we study the white certificate mechanism (which is a credit‐based trading mechanism) used in Italy to promote EE and assess its implementation in Chile through an ex‐ante simulation. The main idea of this mechanism is that the regulation authority fixes an amount of energy savings (which minimizes the total cost of producing the needed energy supply) and obligates gas and electricity distribution companies to obtain enough certificates to reach that target. We study several benefits of the reduction in energy consumption using a social‐economic project assessment methodology. We find that there are large economic benefits of implementing a white certificate scheme in Chile.

Select this Article		Implementation of the German Passivhaus concept in South‐East Europe. Considerations for Romania Viorel Badescu1 and Nicolae Rotar Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000066 Posted ahead of print 27 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract The first passive house (PH) has been built in Germany in 1991. Since then several empirical design solutions were developed, allowing fulfilling the requirements of the PH standard proposed by the Passive House Institute (PHI) of Darmstadt. These design solutions spread out in Central and Western Europe and there is a tendency to be implemented in areas with quite different climate than Germany, such as South‐East Europe. This paper focuses on the question: would the German design solutions ensure the fulfillment of PH standard requirements under the latitudes of Romania? The paper compares general climate conditions for twenty‐two towns in Germany and Romania. Further analysis is performed by estimating the energetic performance of a prototype passive building when located in any of the twenty‐two towns of Germany and Romania. The prototype passive building is AMVIC PH built in 2008 in Bragadiru (near Bucharest, Romania). It appears that the design solutions developed in Germany may be relaxed (i.e., for example, the thermal insulation may be reduced) when implemented for latitudes lower than 45 deg. North.

Select this Article		Thermal Energy Performance of a Solar Thermal Electric Panel (STEP) Stuart Baur, Member, ASCE and Lamson Joel Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000065 Posted ahead of print 23 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract The main goal of this research was to develop and understand the performance of a hybrid roof system that combined an amorphous junction photovoltaic panel in combination with copper panel and tubing encased in a low‐iron glass. The setup encompassed 160 square feet of the solar thermal electric panel (STEP) system supplied with a glycol‐water closed‐loop system. The system was fixed to a simulated roof assembly built at the optimal angle of 61° for winter solstice for the local area (Rolla, Missouri). The encased combination panel provided consistent electrical efficiency while mixed thermal efficiencies based on the hours of operation. In conclusion this paper will discuss experimental performance analysis on the STEP system thermal and overall outcomes. Further testing on the affects of a glazed versus unglazed panel yielded a 23percnt; reduction in solar electric production, however it increased thermal collection by approximately 200percnt;. The present study shows that the idea of a STEP system is viable. A prototype hybrid solar thermal electric panel system was implemented in the university's solar house entry into the 2005 solar decathlon and today the solar house is part of student housing and solar research facility here on campus.

Select this Article		Quantifying System‐Level Benefits from Distributed Solar and Energy Storage Shisheng Huang, Jingjie Xiao, Joseph F. Pekny, Gintaras V. Reklaitis, and Andrew L. Liu Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000064 Posted ahead of print 7 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Microgeneration using solar photovoltaic (PV) systems is one of the fastest growing applications of solar energy in the United States. Its success has been partly fueled by the availability of net metering by electric utilities. However, with increasing solar PV penetration, the availability of net metering is likely to be capped. Households would then need to rely on distributed storage to capture the full benefits of their installed PV systems. Although studies of these storage systems to assess their benefits to the individual household have been examined in literature, the system‐wide benefits have yet to be fully examined. In this study, the utility level benefits of distributed PV systems coupled with electricity storage are quantified. The goal is to provide an estimate of these benefits so that these savings can potentially be translated into incentives to drive more PV investment. An agent‐based residential electricity demand model is combined with a stochastic programming unit commitment model to determine these effects. A case study based on the California residential sector shows that at 10% penetration levels for households with a 4 kW solar PV panel with a 0.5 kWh battery, the daily systems cost savings per household could be over $5 a day in August.

Select this Article		Combined Cycle Power Plant Performance Analyses Based on the Single and Multi Pressure Heat Recovery Steam Generator Murad A. Rahim Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000063 Posted ahead of print 7 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract In this study sensitivity analysis is performed for single, double and triple pressure heat recovery steam generators in a combined cycle power plant. Steam pressure, evaporator pinch point and economizer approach temperature differences are taken as design parameters. Temperature‐Heat (T‐Q) graphics of HRSG designs and the effects of design parameters to the plant efficiency, net power production and heat transfer areas are obtained. The calculated results are useful to compare single and multi pressure HRSGs in a combined cycle power plant scheme. In single, double and triple pressure HRSG, net power increment is about 0.05, 0.28 and 0.29 % at every 10 bar inlet pressure increment. The net power output of the cycle decreases with increasing evaporator pinch point temperature difference. For single pressure HRSG, this decrement is about 0.54% while for double and triple pressure HRSG it is about 0.21% and 0.17%, respectively. For every 1°C increment in economizer approach temperature makes a decrement of about 0.09% and for double and triple pressure 0.037% 0.018%, respectively. However, net heat transfer area is also decreased and it is directly related to the first investment cost of the HRSG. Therefore, approach temperature and pinch point temperature should be taken into account for the optimum design of heat recovery steam generators.

Select this Article		Development of Photovoltaic Power Generation in China: Potential, Energy Conservation and Emission Reduction Benefits Zhongfu Tan, Huijuan Zhang, Jun Xu, Jianhui Wang, Chao Yu, and Jinliang Zhang Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000062 Posted ahead of print 23 November 2011 Full Text: \| Download PDF
	+ -	Show Abstract Photovoltaic (PV) power generation is a significant way to deal with the energy crisis and protect the environment both in China and overseas. On the basis of analysis of the four factors that impact the development of China's PV power generation, including solar energy resources in China, PV industry conditions, research and development of solar cell technology, and related PV policies, the prospects and development potential of PV power generation in China are discussed. Using actual data on China's PV power generation, the cost of PV modules and the potential decrease in the initial investment required to establish PV systems are analyzed, and the declining trends in the generation cost and purchase price of PV power in China are estimated. The economic feasibility of PV power generation is studied by comparing the trends of generation costs for PV and thermal power. Finally, the energy conservation and emission reduction benefits of PV power generation are analyzed.

Select this Article		Technoeconomic Sensitivity of Biobased Hydrocarbon Production via Fast Pyrolysis to Government Incentive Programs Tristan R. Brown and Guiping Hu Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000061 Posted ahead of print 8 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Fast pyrolysis and upgrading is a promising thermochemical pathway that produces pyrolysis oil that can be upgraded via hydroprocessing into hydrocarbon‐based transportation fuels (drop‐in biofuels). The internal rate of return (IRR) of a fast pyrolysis and upgrading facility is a function of feedstock cost and projected revenues. We calculate the IRR of a fast pyrolysis and upgrading facility under six different policy scenarios: [1] a baseline scenario in which the facility receives no government support; [2] a scenario in which cap‐and‐trade (H.R. 2454) is enacted with both carbon price and offsets; [3] a scenario in which the Volumetric Ethanol Excise Tax Credit (VEETC) is modified to include drop‐in biofuels; [4] a scenario in which the VEETC is replaced with a variable VEETC; [5] the revised Renewable Fuel Standard (RFS2); and [6] the Cellulosic Biofuel Producer Tax Credit (CBPTC). Combinations of these policy scenarios are also analyzed. We find that the policies responsible for increasing the value of pyrolysis products increase facility IRR the most, while policies minimizing facility tax burden have an only marginal effect on IRR.

Select this Article		Influence of the Blade Hub Geometry on the Performance of Low Head Axial Flow Turbines Punit Singh and Franz Nestmann Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000060 Posted ahead of print 19 September 2011 Full Text: \| Download PDF
	+ -	Show Abstract The influence of geometric parameters like blade profile and hub geometry on axial flow turbines for micro hydro application remains poorly characterized. This paper firstly introduces a holistic theoretical model for studying the hydraulic phenomenon resulting from geometric modification to the blades. It then describes modification carried out on two runner stages, of which one has untwisted blades and the other has twisted blades obtained by modifying the inlet hub. The experimental results showed that the performance of the untwisted blade runner was satisfactory with a maximum efficiency of 68%. However, positive effects of twisted blades were clearly evident with an efficiency rise of more than 2%. It also looks into the possible limitations of the model and suggests the extension of the experimental work and the use of computational tools to carryout a progressive validation of all experimental findings, especially on the flow physics within the hub region and the slip phenomena. The paper finally underlines the importance of developing a standardization philosophy for axial flow turbines specific for micro hydro requirements.

Select this Article		Experimental Investigation on Adjustable Ejector Performance Kun Zhang, Shengqiang Shen, Yong Yang, and Xingwang Tian Journal of Energy Engineering doi:http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000058 Posted ahead of print 13 August 2011 Full Text: \| Download PDF
	+ -	Show Abstract An experimental study on the performance of an adjustable ejector is presented. An axial spindle extending into the nozzle is used to change the throat area of the nozzle adjust to make the ejector adjustable. The variation of operation parameters, such as pressure, temperature and entrainment ratio was investigated for several typical spindle positions. The tests observe that when nozzle throat cross‐section area of the adjustable ejector reduced, the entrainment ratio raised at the expense of the falling of discharge pressure. These characteristics of the adjustable ejector provide potential for more economical design and operation.