Abstract
This paper presents a model for calculating and analyzing the global efficiency of a trigeneration system (CCHP) using 3 reciprocating internal combustion engines (RICE) as prime mover for heat and electric loads. RICE operate simultaneously and at the same load. The CCHP plant delivering energy for the office buildings of an economic operator includes also 2 absorption chillers with water-lithium bromide solution for air conditioning. The system has been analyzed for RICE partial load operation mode, linking the thermal energy output to the cooling power generation. The amount of thermal energy production is influenced by the required energy for cooling. The total cooling load in the summer is determined by both the indoor office-rooms cooling load and the data center cooling load (the energy dissipated by the data center’s components and electrical circuits). An vapor-compression chiller is operated for cooling peak load. During yearly thermal load variation, RICE are switched on or off, operate at nominal capacity or in partial load mode. The thermal efficiency of each engine changes according to the demanded heating load, determining the global efficiency variation of the trigeneration system.. The electrical efficiency of the system is also dependent on the RICE operating load that leads the electric generators. The EER factor for the absorption chillers results accordingly at partial or nominal load operating mode. The functioning graphics for each system equipment were developed based on the thermal load curve of the RICEs and the global efficiency variation graph of the trigeneration system was plotted. Finally, conclusions resulted regarding the optimal functioning of the studied trigeneration system.
Highlights
Trigeneration technologies are already known for decades, they mean the combined production of electricity, heating and cooling, using a single fuel source
Regarding reciprocating internal combustion engines (RICE), the literature mentions the main benefits: works at low fuel consumption at nominal powers, long life and high efficiency, quick start for fast electrical network balancing, wide range of capabilities, the ability to operate at partial loads, the ability to operate at relatively low natural gas pressures [2]
The CCHP plant consists of 3 RICE for the production of the thermal agent and electrical energy, a hot water boiler for the peak thermal load, two absorption chillers for air conditioning and a vaporcompression chiller for cooling peak load
Summary
Trigeneration technologies are already known for decades, they mean the combined production of electricity, heating and cooling, using a single fuel source. According to the prime mover the following technologies can be identified [1]: steam turbines, gas turbines, microturbines, combined cycle gas turbines, reciprocating internal combustion engines (RICE) and new emerging technologies such as organic rankine cycle, Stirling engines, fuel cells. Regarding RICE, the literature mentions the main benefits: works at low fuel consumption at nominal powers, long life and high efficiency, quick start for fast electrical network balancing (about 3 min.), wide range of capabilities (from 50 kW to 9.5 MWel), the ability to operate at partial loads, the ability to operate at relatively low natural gas pressures (about 50 mbar) [2]
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