Engine Cogeneration Research Articles

Integration of trigeneration in an indirect cascade refrigeration system in supermarkets

This article presents an energy and economic analysis of a trigeneration configuration for supermarket applications. The energy system in a supermarket is relatively complex, because it includes lighting, air conditioning, cabinets, refrigeration system, etc. A trigeneration system could be used to simultaneously satisfy heating, refrigeration and electricity demands in supermarkets. More specifically, this article studies the integration of a trigeneration system and an indirect refrigeration cascade compression system in a supermarket in Barcelona. The trigeneration system consists of a cogeneration engine and an ammonia/water absorption chiller unit. The results of simulating energy usage, life cycle costs and CO2 emissions have been compared with a conventional indirect refrigeration cascade compression system for the supermarket studied. Several trigeneration configurations have been studied. They all show a payback time of less than 6 years but the profitability of the investment depends strongly on the ratio between the prices of natural gas and electricity. This study shows that this novel trigeneration system is economically feasible and environmentally more viable than conventional supermarket systems.

DC Linked Hybrid Generation System with an Energy Storage Device including a Photo-Voltaic Generation and a Gas Engine Cogeneration for Residential Houses

For the past few years, a hybrid generation system including solar panel and gas cogeneration is being used for residential houses. Solar panels can generate electronic power at daytime; meanwhile, it cannot generate electronic power at night time. But the power consumption of residential houses usually peaks in the evening. The gas engine cogeneration system can generate electronic power without such a restriction, and it also can generate heat power to warm up house or to produce hot water. In this paper, we propose the solar panel and gas engine co-generation hybrid system with an energy storage device that is combined by dc bus. If a black out occurs, the system still can supply electronic power for special house loads. We propose the control scheme for the system which are related with the charging level of the energy storage device, the voltage of the utility grid which can be applied both grid connected and stand alone operation. Finally, we carried out some experiments to demonstrate the system operation and calculation for loss estimation.

410 太陽電池を併設したガスエンジンコージェネレーションシステムの最適運用計画 : 運用方策および省エネルギー性に関する分析(エネルギー有効利用,蓄熱)

410 太陽電池を併設したガスエンジンコージェネレーションシステムの最適運用計画 : 運用方策および省エネルギー性に関する分析(エネルギー有効利用,蓄熱)

155 分散型エネルギーシステムにおける熱利用プロセスのモデルベース性能監視 : 過渡状態での動的補償を用いた性能監視

A model-based performance monitoring method for a heat utilization process in a distributed energy system is developed in this study. The performance monitoring has three components: a static input-output model for the target process, a dynamic compensation function, and a failure detection function. First, the static input-output model estimates the output process variables in response to the variations in the input process variables. Then, the dynamic characteristics of the output process variables are provided in the dynamic compensation function where they are indentified as first order lag systems. Finally, the estimated output process variables considering the dynamic characteristics are compared with the measured output process variables in order to detect device failures. Through a numerical simulation for a heat utilization process in a gas engine cogeneration system that has a radiator with a considerable lag characteristic, the effectiveness of the developed performance monitoring method in a transient state is verified. The result shows the sufficiency of the estimation accuracy of the output process variables and the capability of detecting device failures in a transient state.

G080014 ビル用エネルギー供給システムの最適更新計画における各種代替システムの経済性評価([G08001]動カエネルギーシステム部門一般セッション(1):動力エネルギーシステムの高度化1)

In this paper, a method of rationally determining an optimal renewal plan is proposed for energy supply systems based on the optimization approach. In the planning of this proposed method, it becomes necessary to consider many factors such as the deterioration of each pieces of existing equipment, candidate pieces of equipment with upgraded efficiency reflecting technology improvement in the proper renewal year, the structure of renewal system, and so on. It is also necessary to determine the system's operational policy to match energy demands, which change daily and hourly through the year. A numerical study is carried out for a hospital with the total floor area of 25 000m2, where electrical (e.g., heat pump) and gas (e.g., gas engine cogeneration) systems are compared together with theircombination of gas and electricity driven equipment (hybrid) system. Through this numerical study, the following results are obtained: a) Theoretically, the hybrid system is, of course, the best renewal system. However, the economic difference between the hybrid and the electrical systems is very small. b) The gas system is worse economically than the electrical one relatively due to the low energy efficiency of the related equipment, the high price of energy, and so on.

Optimal sizing of residential gas engine cogeneration system for power interchange operation from energy-saving viewpoint

A power interchange operation, in which electricity generated by residential gas engine cogeneration systems is shared among the residences in a housing complex without a reverse power flow to a commercial electric power system, has a high energy-saving effect. In this study, the optimal sizing of the residential gas engine cogeneration system for the power interchange operation is discussed from the energy-saving viewpoint by conducting optimal operational planning based on mixed-integer linear programming. First, the scale effect of the residential gas engine cogeneration system on its performance is identified from the nominal performances of commercial devices. Then, the energy-saving effect of the power interchange operation is analyzed from the optimal operation patterns for various system scales. The result shows that the energy-saving effect increases with the system scale because the heat to power ratio of the system decreases and approaches that of the demand because of the increase in generating efficiency. However, systems with a rated electric output larger than 1 kW exhibit almost the same energy-saving effect. Hence, it is concluded that a system with a rated electric output of 1 kW, which is a commercial device for residential applications, is the optimal scale for the power interchange operation.

Modeling of a thermal energy storage system coupled with combined heat and power generation for the heating requirements of a University Campus

The optimum efficiency in the exploitation of a given energy resource in the cogeneration of electrical power and thermal energy requires the simultaneity of the electrical and thermal demands. Moreover, when the thermal demand is strongly time-varying or even discontinuous, the use of a thermal energy storage coupled with the cogeneration engine provides an attractive solution by allowing the production of dispatchable electrical power while more profitably exploiting the thermal energy available from the prime mover. The excess cogenerated heat can in fact be stored and then dispatched later when it is required by the thermal load. In the present work the simulation of a cogeneration facility coupled with a thermal energy storage system is considered. In order to assess and quantify the validity of such a solution, a practical case study is analysed: the model is applied to match the heating requirement of the buildings belonging to University of Parma Campus. The results of the energetic and economical analysis confirm the effectiveness of this solution strategy, based on the thermal energy storage system, by providing important guidelines in the choice of its optimal size.

Power Hardware-in-the-loop Simulation of a Gas Engine Cogeneration System for Developing a Power Converter System

This research focuses on the development scheme of a power converter in a gas engine cogeneration system using a power hardware-in-the-loop simulation. A matrix converter is adopted to substitute a conventional ac/dc/ac converter and transfers three phase electricity to single phase electricity directly. To inevstigate the interaction between gas engine-generator unit and the proposed matrix converter, a power hardware-in-the-loop simulation is carried out, in which a piece of real matrix converter is installed in the simulation loop and interfaces with the numerical model of gas engine-generator unit. Numerical models of gas engine and generator are presented and verified by experiment. The configuration of the power hardware-in-the-loop simulation is described and results are also presented, through which the practical application of matrix converter is well demonstrated.

Stability and Accuracy Analysis of Power Hardware-in-the-loop Simulation of Inductor Coupled Systems

This paper focuses on the stability issue of power hardware-in-the-loop (PHIL) simulation of inductor coupled systems. Main factors which influence the stability of this type system are analyzed and verified through experiments. A method to resolve the instability problem of the PHIL simulation without decreasing the simulation accuracy is also proposed. Moreover, a PHIL simulation of a gas engine cogeneration system with a matrix converter is introduced and the application of proposed method to improve stability is demonstrated.

STUDY ON ENERGY CONSERVATION EFFECTS OF HOUSING ELECTRICITY AND HEAT SOURCE EQUIPMENTS

This paper presents effects of housing electricity and heat source equipments. We studied about energy saving effects of 4 equipments, CO2 Heat Pump water heater (CO2-HP), Micro Gas Engine Co-Generation System (GE-μCGS), Polymer Electrolyte Fuel Cell Co-Generation System (PEFC-CGS), and Solid Oxide Fuel Cell Co-Generation System (SOFC-CGS). As the result, we have found that energy consumption and CO2 emission reduction rate is the highest in case of SOFC-CGS. Energy consumption is reduced by 17-20% using SOFC-CGS on Electric Power Load Tracking Operation, and 44-47% on Rated Operation. And CO2 emission is reduced by 5-20% on Electric Power Load Tracking Operation and 22-46% on Rated Operation.

An experimental investigation on engine performance and emissions of a supercharged H 2-diesel dual-fuel engine

This study investigated the engine performance and emissions of a supercharged engine fueled by hydrogen and ignited by a pilot amount of diesel fuel in dual-fuel mode. The engine was tested for use as a cogeneration engine, so power output while maintaining a reasonable thermal efficiency was important. Experiments were carried out at a constant pilot injection pressure and pilot quantity for different fuel-air equivalence ratios and at various injection timings without and with charge dilution. The experimental strategy was to optimize the injection timing to maximize engine power at different fuel-air equivalence ratios without knocking and within the limit of the maximum cylinder pressure. The engine was tested first with hydrogen-operation condition up to the maximum possible fuel-air equivalence ratio of 0.3. A maximum IMEP of 908 kPa and a thermal efficiency of about 42% were obtained. Equivalence ratio could not be further increased due to knocking of the engine. The emission of CO was only about 5 ppm, and that of HC was about 15 ppm. However, the NO x emissions were high, 100–200 ppm or more. The charge dilution by N 2 was then performed to obtain lower NO x emissions. The 100% reduction of NO x was achieved. Due to the dilution by N 2 gas, higher amount of energy could be supplied from hydrogen without knocking, and about 13% higher IMEP was produced than without charge dilution.

Performance and emissions of a supercharged dual-fuel engine fueled by hydrogen-rich coke oven gas

This study investigated the engine performance and emissions of a supercharged dual-fuel engine fueled by hydrogen-rich coke oven gas and ignited by a pilot amount of diesel fuel. The engine was tested for use as a cogeneration engine, so power output while maintaining a reasonable thermal efficiency was important. Experiments were carried out at a constant pilot injection pressure and pilot quantity for different fuel-air equivalence ratios and at various injection timings without and with exhaust gas recirculation (EGR). The experimental strategy was to optimize the injection timing to maximize engine power at different fuel-air equivalence ratios without knocking and within the limit of the maximum cylinder pressure. The engine was tested first without EGR condition up to the maximum possible fuel-air equivalence ratio of 0.65. A maximum indicated mean effective pressure (IMEP) of 1425 kPa and a thermal efficiency of 39% were obtained. However, the nitrogen oxides (NOx) emissions were high. A simulated EGR up to 50% was then performed to obtain lower NOx emissions. The maximum reduction of NOx was 60% or more maintaining the similar levels of IMEP and thermal efficiency. Two-stage combustion was obtained; this is an indicator of maximum power output conditions and a precursor of knocking combustion.

Ceramic Gas Turbine Development: Need for a 10Year Plan

Ceramic gas turbine development that started in the 1950s has slowed considerably since most of the large-scale ceramic gas turbine development programs of the 1970s–1990s ended. While component durability still does not meet expectations, the prospect of significant energy savings and emission reductions, potentially achievable with ceramic gas turbines, continues to justify development efforts. Four gas turbine applications have been identified that could be commercially attractive: a small recuperated gas turbine (microturbine) with ∼35% electrical efficiency, a recuperated gas turbine for transportation applications with ∼40% electrical efficiency with potential applications for efficient small engine cogeneration, a ∼40% efficient midsize industrial gas turbine, and a ∼63% (combined cycle) efficient utility turbine. Key technologies have been identified to ensure performance and component durability targets can be met over the expected life cycle for these applications. These technologies include a Si3N4 or SiC with high fracture toughness, durable EBCs for Si3N4 and SiC, an effective EBC∕TBC for SiC∕SiC, a durable oxide∕oxide ceramic matrix composite (CMC) with thermally insulating coating, and the next generation CMCs with high strength that can be used as structural materials for turbine components for small engines and for rotating components in engines of various sizes. The programs will require integrated partnerships between government, national laboratories, universities, and industry. The overall cost of the proposed development programs is estimated at U.S. $100M over 10years, i.e., an annual average of U.S. $10M.

Performance and emission comparison of a supercharged dual-fuel engine fueled by producer gases with varying hydrogen content

Abstract This study investigated the effect of hydrogen content in producer gas on the performance and exhaust emissions of a supercharged producer gas–diesel dual-fuel engine. Two types of producer gases were used in this study, one with low hydrogen content (H 2 = 13.7%) and the other with high hydrogen content (H 2 = 20%). The engine was tested for use as a co-generation engine, so power output while maintaining a reasonable thermal efficiency was important. Experiments were carried out at a constant injection pressure and injection quantity for different fuel–air equivalence ratios and at various injection timings. The experimental strategy was to optimize the injection timing to maximize engine power at different fuel–air equivalence ratios without knocking and within the limit of the maximum cylinder pressure. Two-stage combustion was obtained; this is an indicator of maximum power output conditions and a precursor of knocking combustion. Better combustion, engine performance, and exhaust emissions (except NO x ) were obtained with the high H 2 -content producer gas than with the low H 2 -content producer gas, especially under leaner conditions. Moreover, a broader window of fuel–air equivalence ratio was found with highest thermal efficiencies for the high H 2 -content producer gas.

Performance evaluation of an electricity base load engine cogeneration system

Decentralized electricity production by cogeneration can result in primary energy economy, as these systems operate with a high-energy utilization factor (EUF), producing electricity and recovering energy rejected by the prime mover to meet site thermal demands. Because energy demands in buildings vary with such factors as the hour of the day, level of activity and climatic conditions, cogeneration case studies should consider different system configurations, energy demand profiles and climatic profiles. This paper analyzes an engine cogeneration system as an integrated thermal system by means of a computational simulation program. The simulation takes into account characteristics of the system, characteristics of the pieces of equipment, design choices and parameters, the variability of operating conditions, site energy demand profiles and climatic data to evaluate the performance of the cogeneration plant. Performance evaluation is based on: (i) the EUF, (ii) the exergy efficiency and (iii) primary energy savings analysis. Copyright © 2009 John Wiley & Sons, Ltd.

Research on Reduction of Harmonic Distortion of Inverter for Small Gas Engine Cogeneration System with Backup Function

Research on Reduction of Harmonic Distortion of Inverter for Small Gas Engine Cogeneration System with Backup Function

Typical off-design analytical performances of internal combustion engine cogeneration

Based on experimental data, typical off-design characteristic curves with corresponding formulas of internal combustion engine (ICE) are summarized and investigated. In combination with analytical solution of single-pressure heat recovery steam generator (HRSG) and influence of ambient pressure on combined heat and power (CHP) system, off-design operation regularities of ICE cogeneration are analyzed. The approach temperature difference ΔTa, relative steam production and superheated steam temperature decrease with the decrease in engine load. The total energy efficiency, equivalent exergy efficiency and economic exergy efficiency first increase and then decrease. Therefore, there exists an optimum value, corresponding to ICE best efficiency operating condition. It is worth emphasizing that ΔTa is likely to be negative in low load condition with high design steam parameter and low ICE design exhaust gas temperature. Compared with single shaft gas turbine cogeneration, ΔTa in ICE cogeneration is more likely to be negative. The main reason for this is that the gas turbine has an increased exhaust gas flow with the decrease in load; while ICE is on the contrary. Moreover, ICE power output and efficiency decrease with the decrease in ambient pressure. Hence, approach temperature difference, relative steam production and superheated steam temperature decrease rapidly while the cogeneration efficiencies decrease slightly. It is necessary to consider the influence of ambient conditions, especially the optimization of ICE performances at different places, on cogeneration performances.

A08 スターリングエンジン用木質ペレット燃焼器に関する研究(スターリングエンジン及び関連要素と応用システム(2))

Gases burn more efficiently than solids, gasification is used for generating energy from wood pellets Electricity can be generated cleanly by a Stirling engine driven by the heat energy obtained through gasified combustion, along with a cogeneration system, without emitting surplus CO2 into the atmosphere. This study examined the basic combustion characteristics of a wood pellet gasified combustor for a Stirling engine and the performance of a Stirling engine cogeneration system with a wood pellet gasified combustor. A gasified combustor was built, and the combustor temperature and concentration was measured to study the combustion state. As a result, it was revealed that a gasified combustor was suitable for use with a Stirling engine because its exit temperature was higher than that of an ordinary updraft-type combustor. Our prototype combustor was capable of supplying a maximum 18.5KW to a Stirling engine using 23.8KW of fuel, resulting in a heat-to-fuel capacity of 78%.

Effect of power interchange operation of multiple household gas engine cogeneration systems on energy-saving

The effect of power interchange operation of multiple household gas engine cogeneration systems (H-GCGS) on the energy-saving is investigated using an optimization approach based on the mixed-integer linear programming. In this power interchange operation, electricity generated by H-GCGS is shared among households in a housing complex without transmitting to a commercial electric power system so that the operating time of these systems may increase. This paper numerically analyzes optimal operational strategies for 20 households and three types of household energy supply configurations: the power interchange operation of the H-GCGSs (IC), stand-alone operation of each H-GCGSs (SA), and conventional energy supply system without the H-GCGSs. A numerical result clarifies the effectiveness of the power interchange operation from the energy-saving viewpoint and a dominant parameter for evaluating the energy-saving effect.

Polygeneration and efficient use of natural resources

Abstract The consumption of natural resources has been increasing continuously during recent decades, due to the growing demand caused by both the economic and the demographic rise of global population. Environmental overloads that endanger the survival of our civilization and the sustainability of current life support systems are caused by the increased consumption of natural resources—particularly water and energy—which are essential for life and for the socio-economic development of societies. While not yet well utilized, process integration and polygeneration are promising tools which reach the double objective of increasing the efficiency of natural resources, and also minimizing the environmental impact. This paper discusses the concepts of polygeneration and energy integration and various examples of polygeneration systems: (i) sugar and energy production in a sugarcane factory; (ii) district heating and cooling with natural gas cogeneration engines and (iii) combined production of water and energy. It is clearly evident that polygeneration systems which include appropriate process integration significantly increase the efficient use of natural resources.