Application areas of Trigeneration

Thermal chillers are already used in small and medium size capacity range in order to cool separate buildings or rooms.

The heat for cooling can be provided via different ways:

District heating system
Decentralized combined heat and power unit
Solar panels

The usage of combined heat and power units or solar panels may require an additional heating source e.g. a boiler, in order to be able to cover the peak load.

District or local cooling systems can be used for medium to high capacity requirements. The cooling takes places mostly via a separate cold water system and large distances. This will require high investments for the pipelines as well as the maintenance of the system.

Application areas in regards to required cooling level:

Figure 1: Application areas of different cooling technologies

Source: Own diagram adapted from Hesselbach: "Energie- und klimaeffiziente Produktion" (adapted from Müller, 2009, „Energieeffiziente Fabriken planen und betreiben; p. 203“), p.215, Publisher: Springer Vieweg

Description:

The graph shows the possible application areas of cooling from compression or thermally driven chillers depending on the required cooling level. Cooling via thermally driven chiller can be used for all areas except the extremist cooling below 50°C, whereas cooling with electric compression chillers is able to cover all levels of cooling requirements.

The advantages of adsorption technology in contrast to electric compression chillers:

Source: „Kühlen und Klimatisieren mit Wärme“ (Fraunhofer IRB Verlag; Stuttgart; Hans Martin-Henning; Thorsten Urbaneck at al., Pages 31 ff.):

Advantages of Absorption chillers in contrast to electric compression chillers:	Disadvantages of Absorption chillers in contrast to electric compression chillers:
Technology and Implementation:
Simple Mechanic, less movable parts	Larger and heavier construction Heat emission to the environment at a relatively low temperature level
Functioning and Maintenance of the system:
Usage of heat as power source for thermic compressor Low noise and susceptibility of failure Low maintenance Favorable partial load behavior (up to 10% of required capacity) Long time of usage if high water quality is provided	Higher effort for re-cooling Slow performance in contrast to electric compression chiller Qualified personnel for maintenance and operation required Complicated leak detection
Energy efficiency
Saving of high-quality electricity in contrast to conventional compression chiller Need of electricity only for the operation of the pumps for the coolant and solvent	Circulation of greater cooling water volume
Economic Efficiency
Low operating costs if heat or waste heat is available at low cost	Higher investments (Absorption chiller approx. 250 to 350 Euro /kW cooling capacity), especially for smaller capacity range In contrast: Electric compression chillers: 75 to 275 Euro/kW cooling capacity)

Table 1: Advantages and Disadvantages of Absorption Chillers

The most important factor for the economic efficient usage of Trigeneration with thermally driven chiller machines, is the availability of heat at low costs or waste heat. Another possibility is the direct heating of the thermally driven chiller, which means that the heat is not generated by the cogeneration plant. However, this cannot be recommended due to ecological and energy-economic reasons. This approach is still widely spread in Non-European countries as the United States or Japan.