Experimental and Numerical Study of a Microcogeneration Stirling Unit under On–Off Cycling Operation

Stirling units are a viable option for micro-cogeneration applications, but they operate often with multiple daily startups and shutdowns due to the variability of load profiles. This work focused on the experimental and numerical study of a small-size commercial Stirling unit when subjected to cycling operations. First, experimental data about energy flows and emissions were collected during on–off operations. Second, these data were utilized to tune an in-house code for the economic optimization of cogeneration plant scheduling. Lastly, the tuned code was applied to a case study of a residential flat in Northern Italy during a typical winter day to investigate the optimal scheduling of the Stirling unit equipped with a thermal storage tank of diverse sizes. Experimentally, the Stirling unit showed an integrated electric efficiency of 8.9% (8.0%) and thermal efficiency of 91.0% (82.2%), referred to as the fuel lower and, between parenthesis, higher heating value during the on–off cycling test, while emissions showed peaks in NOx and CO up to 100 ppm but shorter than a minute. Numerically, predictions indicated that considering the on–off effects, the optimized operating strategy led to a great reduction of daily startups, with a number lower than 10 per day due to an optimal thermal storage size of 4 kWh. Ultimately, the primary energy saving was 12% and the daily operational cost was 2.9 €/day.

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Engineering-Economic Optimization of a Fuel Cell Cogeneration Plant

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2906814 ◽

1994 ◽

Vol 116 (1) ◽

pp. 8-14 ◽

Cited By ~ 8

Author(s):

Y. Matsumoto ◽

R. Yokoyama ◽

K. Ito

Keyword(s):

Fuel Cell ◽

Energy Savings ◽

Numerical Study ◽

Capital Cost ◽

Optimization Approach ◽

Cogeneration Plant ◽

Economic Optimization ◽

Maximum Utility ◽

Annual Total ◽

Electrical Demand

The feasibility of fuel cells in cogeneration applications is studied from engineering and economic viewpoints by using an optimization approach. Capacities of fuel cell cogeneration units and auxiliary devices are determined together with maximum utility demands so as to minimize the annual total cost by considering the plant’s annual operational strategy. This optimization problem is solved efficiently by considering the hierarchical relationship between unit sizing and operational planning problems. Through a numerical study on a plant for installation in a hotel and office building with a maximum electrical demand of 1000 kW, the effect of initial capital cost of fuel cell cogeneration units is examined from the perspective of the plant capacity, economics, and energy savings. The results show that a fuel cell cogeneration plant may have better economic and energy-saving characteristics than a conventional gas engine cogeneration plant with a reduction in the capital cost of fuel cell.

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Multi-objective Optimization in Unit Sizing of a Gas Turbine Cogeneration Plant

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2812781 ◽

1995 ◽

Vol 117 (1) ◽

pp. 53-59 ◽

Cited By ~ 11

Author(s):

R. Yokoyama ◽

K. Ito

Keyword(s):

Gas Turbine ◽

Energy Demand ◽

Numerical Study ◽

District Heating ◽

Primary Energy ◽

Cogeneration Plant ◽

Multi Objective Optimization ◽

Weighting Method ◽

Multi Objective ◽

Heating And Cooling

An optimal planning method for cogeneration plants proposed earlier is extended to the case with multiple optimization criteria. Equipment capacities and utility maximum demands are determined so as to minimize both the annual total cost and the annual primary energy consumption in consideration of plants’ operational strategies for energy demand requirements. This problem is considered as a multi-objective optimization one, and a discrete set of Pareto optimal solutions is derived numerically by the weighting method. Through a numerical study on a simple cycle gas turbine cogeneration plant used for district heating and cooling, a trade-off relationship between the economic and energy-saving properties is clarified.

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Optimal Operational Planning of Cogeneration Systems With Thermal Storage by the Decomposition Method

Journal of Energy Resources Technology ◽

10.1115/1.2835432 ◽

1995 ◽

Vol 117 (4) ◽

pp. 337-342 ◽

Cited By ~ 17

Author(s):

R. Yokoyama ◽

K. Ito

Keyword(s):

Energy Demand ◽

Decomposition Method ◽

Large Scale ◽

Numerical Study ◽

Thermal Storage ◽

Operational Planning ◽

Mixed Integer ◽

Operational Cost ◽

Cogeneration System ◽

Method Effects

An optimal operational planning method is proposed for cogeneration systems with thermal storage. The daily operational strategy of constituent equipment is determined so as to minimize the daily operational cost subject to the energy demand requirement. This optimization problem is formulated as a large-scale mixed-integer linear programming one, and it is solved by means of the decomposition method. Effects of thermal storage on the operation of cogeneration systems are examined through a numerical study on a gas engine-driven cogeneration system installed in a hotel. This method is a useful tool for evaluating the economic and energy-saving properties of cogeneration systems with thermal storage.

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Cogeneration Plant on Biomass - Case Study

The Scientific Bulletin of Electrical Engineering Faculty ◽

10.1515/sbeef-2017-0027 ◽

2018 ◽

Vol 18 (2) ◽

pp. 7-11 ◽

Cited By ~ 2

Author(s):

A. Enescu ◽

E. Diaconu

Keyword(s):

Energy Savings ◽

High Efficiency ◽

Primary Energy ◽

Hot Water ◽

Raw Material ◽

Cogeneration Plant ◽

The Social ◽

The One ◽

The Impact

AbstractThe concept of cogeneration defines the simultaneous production with the same installation of electric and thermal energy (in the form of hot water or steam). High-efficiency cogeneration implies that cogeneration production should ensure primary energy savings of at least 10% compared to the reference values of separate production of electricity and heat. This paper presents the process of functioning of a cogeneration plant, operating in the Suceava county, Romania, referring to the actual values regarding the consumption and the proportions of the raw material on the one hand and the energy produced on the other. It also describes the entire production process as well as the impact on the environment, the social and economic aspects of the implementation of such a project.

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Influence of Fuel Cost on the Operation of a Gas Turbine-Waste Heat Boiler Cogeneration Plant

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2906466 ◽

1990 ◽

Vol 112 (1) ◽

pp. 122-128 ◽

Cited By ~ 21

Author(s):

K. Ito ◽

R. Yokoyama ◽

S. Akagi ◽

Y. Matsumoto

Keyword(s):

Gas Turbine ◽

Waste Heat ◽

District Heating ◽

Planning Method ◽

Operational Cost ◽

Cogeneration Plant ◽

Fuel Cost ◽

Waste Heat Boiler ◽

Heating And Cooling

The influence of fuel cost on the operation is investigated for a gas turbine-waste heat boiler cogeneration plant by an optimal operational planning method. A planning method is first presented by which the operational policy of each piece of constituent equipment is determined so as to minimize the operational cost. Then, a case study is performed for a cogeneration plant used for district heating and cooling. Through the study, it is made clear how the optimal operational policy and the economic or energy conservative properties are influenced by the costs of purchased electric power and natural gas. It is also shown that the optimal operational policy is superior in economy as compared with other conventional ones.

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Mobile Money - A Catalyst for Financial Inclusion in Developing Economies: A Case Study of Zimbabwe using FinScope Survey Data

GIS Business ◽

10.26643/gis.v12i4.3431 ◽

2016 ◽

Vol 12 (4) ◽

pp. 45-56

Author(s):

Kingstone Mutsonziwa ◽

Obert K. Maposa

Keyword(s):

Rural Communities ◽

Developing Economies ◽

Adult Population ◽

Financial System ◽

Financial Inclusion ◽

Viable Option ◽

Mobile Money ◽

Bank Branches ◽

Financial Transactions

Mobile money in Zimbabwe has extensively extended the frontiers of financial inclusion to reach millions who were earlier excluded within a relatively short space of time. The growing use of mobile phones in transferring money and making payments has significantly altered the countrys financial inclusion landscape as millions who had been hitherto excluded can now perform financial transactions in a relatively cheap, reliable and secure way. The FinScope results found out that 45% of the adult population use mobile money services. Of those using mobile money, 65% mentioned that is convenient, while 36% mentioned that it is cheap. Mobile money is accessible. These drivers are in the backdrop of few or no bank branches in rural communities as well as time and cost of accessing the bank branches. In Zimbabwe, mobile money is mostly used as a vehicle for remittances. While some people are enjoying mobile money services, it is important to mention that there are still people who are excluded from the formal financial system. The reasons why people do not use mobile money are mainly related to poverty issues. Mobile money remains a viable option to push the landscape of financial inclusion in Zimbabwe and other emerging markets where the formal financial system might not be strong.

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