Elsevier

Applied Energy

Volume 88, Issue 12, December 2011, Pages 4424-4440
Applied Energy

Performance analysis of a trigeneration system based on a micro gas turbine and an air-cooled, indirect fired, ammonia–water absorption chiller

https://doi.org/10.1016/j.apenergy.2011.05.021Get rights and content

Abstract

The objective of this paper is to experimentally determine the efficiency and viability of the performance of an advanced trigeneration system that consists of a micro gas turbine in which the exhaust gases heat hot thermal oil to produce cooling with an air cooled absorption chiller and hot water for heating and DHW. The micro gas turbine with a net power of 28 kW produces around 60 kW of heat to drive an ammonia/water air-cooled absorption chiller with a rated capacity of 17 kW. The trigeneration system was tested in different operating conditions by varying the output power of the micro gas turbine, the ambient temperature for the absorption unit, the chilled water outlet temperature and the thermal oil inlet temperature. The modelling performance of the trigeneration system and the electrical modelling of the micro gas turbine are presented and compared with experimental results. Finally, the primary energy saving and the economic analysis show the advantages and drawbacks of this trigeneration configuration.

Highlights

► Design and construction of a trigeneration system with a micro gas turbine and an air-cooled ammonia/water absorption chiller. ► Energy analysis of the selected configuration. ► Monitoring and analysis of the system performance in a test bench. ► Thermal and electrical modelling using the experimental results at the test bench. ► Calculation of the energetic and economic viability of this system for the building sector.

Section snippets

Introduction and objectives

Trigeneration is the simultaneous production of mechanical power (usually converted into electricity), heat and cooling using a single source of primary energy such as fossil fuel or renewable energy sources. The thermal energy recovered from a prime mover—usually an engine or micro gas turbine (MGT)—is used to generate cooling with a thermally driven cooling system. A well designed trigeneration system is usually more energy efficient than the conventional separate production of electricity,

Description and design

The main criteria for selecting the components and designing the trigeneration system were: high overall energy efficiency, reduced size, dry heat rejection for the absorption chiller and good recovery of the waste heat in the MGT exhaust gases.

Fig. 1 shows the configuration of the trigeneration system analysed in this paper. In the MGT tested the combustion air is first used to cool the permanent magnet electric generator and later compressed and forced into the cold side of a regenerator,

Test bench description and data analysis methodology

The trigeneration system was tested in the CREVER’s new test bench at the Rovira i Virgili University in Tarragona (Spain). The absorption chiller was installed in an environmental chamber KZ/80 (temperature range −40 °C to 90 °C) with 80 mm PUR-foam wall insulation, so that its performance could be evaluated in a controlled environment at steady state. The other trigeneration components were installed next to it outside the chamber (see Fig. 5).

In this test bench the hot and chilled water

Electrical performance analysis

The electric behaviour of the microturbine was studied by developing a model that can reproduce the MGT performance during steady state as well as during electromechanical and electromagnetic transients.

Compatibility between energy supply and demand

The residential building sector, commercial buildings, hotels, small trade, and industry facilities in Mediterranean areas have considerable cooling demands and can be attractive areas in which to integrate trigeneration systems.

The objective of this section is to determine the compatibility between the energy services provided by this trigeneration system and the energy services demanded by the building sector.

The building sector is one of the main energy consumption sectors in the European

Conclusions

This paper presents the viability of the electrical, thermal and cooling performance of a trigeneration system designed to operate with a micro gas turbine (MGT) of 28 kWe, an air cooled absorption chiller and a heat recovery boiler. The ambient temperature and the MGT load were the main variables studied in a test bench because of the considerable effect they have on the efficiency of the trigeneration system.

Higher output power means hotter exhaust gases and, consequently, better performance

Acknowledgements

The authors would like to acknowledge the funding for this work provided by the Spanish government Project ENE2006-15700-C02-01/CON and ENE2009-14182, the Catalan Energy Institute (ICAEN), the Spanish Energy Agency (IDAE) and the European Project HEGEL (Contract No. 20153).

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