**4.2. Other advanced cycles**

An adsorption chiller installed in the University hospital in Freiburg [64]

Backup: thermally driven by steam network of the hospital Daily solar radiation: temperate, central European climate

Main features: solar system is working on assisting the main driving heat system and can deliver about 90% of the heating

Two-bed adsorption chiller developed by SorTech [65]

Daily solar radiation: temperate, central European climate

Main features: developed by SorTech AG, and it enables to paste the heat exchanger surface with silica gel pellets with the aid of epoxy resin without blocking the entrance pores of

Silica gel-water adsorption chiller developed in SJTU [66]

C): 85

 of heat pipe evacuated tubular Main features: the adsorber is a compact finned-tube heat exchanger, the condenser is a shell and tube heat exchanger, and the evaporator cooling is output through a methanol chamber, which acts as a gravity heat pipe. Power

**Table 2.** Summary of some adsorption prototypes.

Adsorption chiller installed in the University hospital

The Fraunhofer ISE institute building and SorTech adsorption chiller in the technical room (sources:

in Freiburg

/h. Heat rejection circuit

of U-type evacuated tube

/h.

/h. Chilled water circuit 18/15°C at 2.0 m<sup>3</sup>

Fraunhofer ISE) [34]

Photo of the adsorption chiller

Working pair: silica gel-water

88 Sustainable Air Conditioning Systems

Solar collector type: evacuated tube

required in mid-day hours (4 hours)

Working pair: silica gel-water

Solar collector type: flat plate

Working pair: silica gel-water

COP: 0.35 (system) 0.15 (solar)

Solar collector type and area: 90 m2

consumption for pumps was 1.87 kW

Regeneration temp. (o

/kW)

27/32°C at 3.7 m<sup>3</sup>

Area: 3.5–4.5 (m2

the pellets

CC(kW): 15

and 60 m2

CC (kW): 7.5 and COP: 0.55 (system) Electricity consumption: 9 W. Heat supply circuit: 72/67°C at 1.6 m<sup>3</sup>

)

CC(kW): 70 and COP –

Area: 170 (m2

There are many of advanced and novel cycles proposed in literature for ARSs. The advanced cycles such as multi-bed cycle, multi-stage cycle and dual-mode cycle are originally developed to make utilize of lower temperature heat sources applicable and more efficient. Another trend in advanced cycles is eliminating the vacuum valves by putting the adsorber, condenser and evaporator in a single chamber to increase the reliability of the system, particularly under the vacuum operating conditions. **Table 2** summarizes data about some applied or prototype adsorption chillers.
