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Besides combined heat and power production GE Jenbacher’s engines also have the ability to operate as combined heat, power and cooling engines (CHPC engines) to generate chilled water which can be used for air conditioning or refrigeration. To achieve this, an absorption chiller is linked to the combined heat and power (CHP) to provide the before mentioned. Quad generation takes this process one step further with the addition of systems to purify carbon dioxide from the engine exhaust.

 

Benefits of trigeneration

 

There are a number of benefits to trigeneration including:

  • Onsite, high efficiency production of electricity and heat

  • Reduced fuel and energy costs

  • Lower electrical usage during peak summer demand

  • Engine heat can be used to produce steam of hot water for onsite use

  • Significant reductions in greenhouse gas emissions

  • No harmful chemical pollutants since water is used as the refrigerant

  • Beneficial for improving building’s energy efficiency ratings

 

Trigeneration systems supply energy in three forms:

  1. Electricity

  2. Heat

  3. Chilled water

 

Absorption chillers provide an economical and environmental alternative to conventional refrigeration. While operating, and with the equipment they use, they allow maximum total fuel efficiency, elimination of harmful refrigerants and the reduction of overall air emissions. There are a number of different configurations of CHP units where refrigeration can be derived. These include:

 

Absorption Chillers

 

  • Operation using hot water

  • Operation using steam

  • Direct heat through combustion

 

Compression-type refrigeration engines

 

  • Direct drive power

  • Electrical drive power

 

A utilization of seasonal excess for heat and cooling is allowed if a cogeneration CHP plant is combined with an absorption refrigerating system. The absorption chiller of the installation operates with the hot water of the cooling circuit of the plant. In accordance to this, the hot exhaust gas from the gas engine can also be used as an energy source for steam generation, which then can be utilized as an energy source for a highly efficient, double-effect steam chiller. Up to 80% of the thermal output of the cogeneration plant is thereby converted to chilled water. In this way, the year round capacity utilization and the overall efficiency of the cogeneration plant can be increased significantly.

 

 

Advantages versus conventional refrigeration

 

Absorption based refrigeration technology offers the most established and economic solution for reduced emission, air conditioning systems.

  • Operated with heat, utilizing relatively inexpensive ‘excess energy’

  • Production of electricity that can be fed into the power grid or used to cover the plant’s electricity requirements

  • During cold seasons, the heat can be utilized to cover heat requirements

  • Absorption chillers have no moving parts and therefore maintenance costs are low.

  • Absorption system has noiseless operation

  • Low operating costs and lifecycle costs

  • Using water as a refrigerant replaces the use of substances which can cause damage to the ozone layer.

 

Key Figures

 

  • Approximately 150-170 kW of cold output is required per 1,000m2 of office space

  • The term tones of refrigeration (TR) is generally used as the unit of cold energy 1 TR (metric) = 3.86 kWh, 1 TR (US) 3.52kWh

  • The term coefficient of performance (COP) is used for referring to the efficiency of an absorption chiller. For a hot water chiller, the COP lies between 0.6 – 0.8 and for a double-effect steam chiller between 1.2 – 1.3

  • Cold water temperatures down to 4.5°C can be achieved with lithium bromide salt

  • Temperatures down to -60°C can be achieved with ammonia