Recoverable Heat for Air Conditioning & Humidity Control

Refrigeration/freezing refers to a direct process end use in which energy is used to lower the temperature of substances or air. Conventional equipment includes chillers and absorption cooling equipment.

Absorption cooling systems require a source of heat. For an ammonia-water cooling system, the heat is required to separate the water and ammonia. In conventional absorption systems, this heat is supplied by steam heat exchangers, an electrical heater or a gas-fired heater. For CHP systems, this heat can be supplied by using a heat exchanger where clean exhaust gases from a turbine or other type of prime mover are used as a heat source. The heating gases may have to be mixed with air or other gases to maintain the desired heating gas temperature. Such a system will reduce or eliminate heat input for the overall system.

This type of heat recovery for cooling is shown below.

Desiccant-based dehumidification systems are used extensively for removing moisture from moist air. These systems are typically used for climate control applications in commercial buildings or industrial process applications. Operation of these systems includes a regeneration step where hot air (or other gases) are used to remove moisture from saturated desiccant media. The chart below is a schematic of this type of system:

In a CHP system, clean exhaust gases will be mixed with ambient air to control the temperature to the desired value. Currently, a variety of heating methods and media are used for supplying hot regenerative air. The heating methods include heating by heat recovery, electricity, steam, or a fuel-fired burner. Application of such a design may require a redesign of the regenerative air system for a retrofit application. For a new application, it can be accounted for during the design phase of the project.

Other technologies for hot heat recovery can be found in our CHP Applications Guide.