Proposed Otto Cycle/Stirling Cycle Hybrid Engine Based Power Generation System

Author(s):  
Barry Cullen ◽  
Jim McGovern

The generation of electrical and thermal power is a matter of critical importance to the modern world. Considerable quantities of both power types are required in all sectors of society; industrial, domestic and leisure, with the future prosperity of both developed and developing societies being dependant on generation of both a sufficient quantity and quality of power. Central to this discussion on the international front is the topic of fossil fuel usage. Despite considerable advances in renewable energy conversion technologies, the human race remains dependant on fossil fuels as a primary energy source. With increasing demand for these finite resources giving rise to strained international relations and economic uncertainty, emphasis has fallen on optimization of usage patterns. The area of power plant efficiency is essential to this optimization. This paper proposes a method for increasing the efficiency of an Otto cycle engine based plant as is typically used in CHP and other Distributed Generation scenarios. The method proposed is to utilise a Stirling cycle engine as a heat recovery device on the exhaust stream of the Otto engine. Thermal energy that may otherwise be lost would thereby be recovered and used to generate additional electrical power. In this manner energy is effectively diverted from the exhaust flow of the engine and converted to mechanical work by way of the Stirling cycle engine. It is postulated that this combined cycle will yield higher plant efficiency than the Otto engine alone. This paper introduces work completed to date and an experimental plan for the project. The project was initiated at undergraduate level as a feasibility study for application of the hybrid engine in automotive circumstances. The study suggested that the combination of the engines in the proposed manner was indeed feasible, with significant power gains possible. However, it proved unlikely that automotive application was the best use of the system unless certain constraints were addressed. Therefore, it was decided to pursue the concept in terms of a stationary generation system. The advantages of the stationary system over the automotive system are addressed briefly, with the constraints of the automotive scenario analysed and their relevance to the stationary generation situation examined. The central areas under investigation are detailed, including thermodynamic theory pertaining to the Otto cycle and Stirling cycle engines, and the combined cycles. Possible limiting factors to the design are discussed also.

2020 ◽  
pp. 99-111
Author(s):  
Vontas Alfenny Nahan ◽  
Audrius Bagdanavicius ◽  
Andrew McMullan

In this study a new multi-generation system which generates power (electricity), thermal energy (heating and cooling) and ash for agricultural needs has been developed and analysed. The system consists of a Biomass Integrated Gasification Combined Cycle (BIGCC) and an absorption chiller system. The system generates about 3.4 MW electricity, 4.9 MW of heat, 88 kW of cooling and 90 kg/h of ash. The multi-generation system has been modelled using Cycle Tempo and EES. Energy, exergy and exergoeconomic analysis of this system had been conducted and exergy costs have been calculated. The exergoeconomic study shows that gasifier, combustor, and Heat Recovery Steam Generator are the main components where the total cost rates are the highest. Exergoeconomic variables such as relative cost difference (r) and exergoeconomic factor (f) have also been calculated. Exergoeconomic factor of evaporator, combustor and condenser are 1.3%, 0.7% and 0.9%, respectively, which is considered very low, indicates that the capital cost rates are much lower than the exergy destruction cost rates. It implies that the improvement of these components could be achieved by increasing the capital investment. The exergy cost of electricity produced in the gas turbine and steam turbine is 0.1050 £/kWh and 0.1627 £/kWh, respectively. The cost of ash is 0.0031 £/kg. In some Asian countries, such as Indonesia, ash could be used as fertilizer for agriculture. Heat exergy cost is 0.0619 £/kWh for gasifier and 0.3972 £/kWh for condenser in the BIGCC system. In the AC system, the exergy cost of the heat in the condenser and absorber is about 0.2956 £/kWh and 0.5636 £/kWh, respectively. The exergy cost of cooling in the AC system is 0.4706 £/kWh. This study shows that exergoeconomic analysis is powerful tool for assessing the costs of products.


Author(s):  
Emanuele Martelli ◽  
Thomas G. Kreutz ◽  
Manuele Gatti ◽  
Paolo Chiesa ◽  
Stefano Consonni

In this work, the “HRSC Optimizer”, a recently developed optimization methodology for the design of Heat Recovery Steam Cycles (HRSCs), Steam Generators (HRSGs) and boilers, is applied to the design of steam cycles for three interesting coal fired, gasification based, plants with CO2 capture: a Fischer-Tropsch (FT) synthesis process with high recycle fraction of the unconverted FT gases (CTL-RC-CCS), a FT synthesis process with once-through reactor (CTL-OT-CCS), and an Integrated Gasification Combined Cycle (IGCC-CCS) based on the same technologies. The analysis reveals that designing efficient HRSCs for the IGCC and the once-through FT plant is relatively straightforward, while designing the HRSC for plant CTL-RC-CCS is very challenging because the recoverable thermal power is concentrated at low temperatures (i.e., below 260 °C) and only a small fraction can be used to superheat steam. As a consequence of the improved heat integration, the electric efficiency of the three plants is increased by about 2 percentage points with respect to the solutions previously published.


2021 ◽  
Vol 25 (4 Part B) ◽  
pp. 2905-2912
Author(s):  
Bowen Wang

In the smart grid context, the article combines SEGS-VI solar thermal power station parameters to establish a solar thermal power generation system model. The thesis is based on the First and Second laws of thermodynamics. It uses the white box model analysis method of the energy system to calculate the solar thermal power generation system-concentrating and collecting subsystem, heat exchange subsystem, and power subsystem to obtain the subsystems dissipation of each process. Finally, the article uses the white box model analysis of the total energy system to treat the subsystems as white boxes, and connects them to form a white box network, makes a reasonable evaluation of the energy consumption status of the total energy system, and finds the weak links in the energy use process of the system. Provide a basis for system energy saving.


2017 ◽  
Vol 1 ◽  
pp. K4MD26 ◽  
Author(s):  
Seyfettin C. Gülen

AbstractThis article evaluates the improvement in gas turbine combined cycle power plant efficiency and output via pressure gain combustion (PGC). Ideal and real cycle calculations are provided for a rigorous assessment of PGC variants (e.g., detonation and deflagration) in a realistic power plant framework with advanced heavy-duty industrial gas turbines. It is shown that PGC is the single-most potent knob available to the designers for a quantum leap in combined cycle performance.


Author(s):  
M. Sato ◽  
T. Abe ◽  
T. Ninomiya ◽  
T. Nakata ◽  
T. Yoshine ◽  
...  

From the view point of future coal utilization technology for the thermal power generation systems, the coal gasification combined cycle system has drawn special interest recently. In the coal gasification combined cycle power generation system, it is necessary to develop a high temperature gas turbine combustor using a low-BTU gas (LBG) which has high thermal efficiency and low emissions. In Japan a development program of the coal gasification combined cycle power generation system has started in 1985 by the national government and Japanese electric companies. In this program, 1300°C class gas turbines will be developed. If the fuel gas cleaning system is a hot type, the coal gaseous fuel to be supplied to gas turbines will contain ammonia. Ammonia will be converted to nitric oxides in the combustion process in gas turbines. Therefore, low fuel-NOx combustion technology will be one of the most important research subjects. This paper describes low fuel-NOx combustion technology for 1300°C class gas turbine combustors using coal gaseous low-BTU fuel as well as combustion characteristics and carbon monoxide emission characteristics. Combustion tests were conducted using a full-scale combustor used for the 150 MW gas turbine at the atmospheric pressure. Furthermore, high pressure combustion tests were conducted using a half-scale combustor used for the 1 50 MW gas turbine.


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