Ammonia heat pumps convert the waste heat from refrigeration into useable high temperature heat, rather than exhausting it to the atmosphere through evaporative condensers.
Heat recovery involves matching a source of waste heat to a practical sink. With conventional refrigeration heat recovery technology, the energy recovered from a compressor’s discharge gas stream is dependent upon the minimum usable temperature of the process receiving the heat (1). Ammonia heat pumps can improve the quality (temperature) of the recovered heat, converting the waste heat from industrial and agricultural refrigeration compressors into useable high temperature heat, rather than exhausting it to the atmosphere through evaporative condensers. The ammonia heat pump can increase heat recovery and offset the on-site consumption of fossil fuels used to power boilers and hot water heaters; adds condensing capacity to existing refrigeration systems, reduces ‘host’ compressor energy; reduces condenser and boiler water consumption, and reduces condenser fan and circulating pump energy.
The ammonia heat pump technology can be applied in pharmaceutical, meat and poultry, seafood, dairy, cold storage warehouses for perishables, and beverage processing applications. Additional energy savings potential exists in industrial drying, distillation, and desalination..
In new facilities or during major plant upgrades, a dual-purpose ammonia heat pump can provide simultaneous cooling and heating. The heat pump recovery technology is new as only seventeen systems are in operation throughout the world today (2014), of which fourteen are in Europe, Canada, and Caribbean islands. Waste heat can be used to heat water to temperatures as high as 195⁰F.
Two to four year simple paybacks are common.
Status:
Baseline Description:
This is not “off-the-shelf” equipment. The heat recovery system must be engineered for each industrial application as existing refrigeration system sizes vary, and process water flow rates and temperatures also vary. A waste heat recovery system installed at a Kraft Foods plant in Iowa provides 7.0 MMBtuh of recovered heat in the form of 145°F washdown water. Coefficient of performance for the heat pump is 6.5 in the summer and 4.2 in the winter.
Simple payback, new construction (years): N/A
Simple payback, retrofit (years): N/A
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.
Project costs include those involved with tapping into an existing ammonia refrigeration system, installation of a custom ammonia heat pump system (with delivery piping), and the electrical energy necessary to operate the high pressure ammonia heat pump system.
This refrigeration system waste heat recovery technology works best in areas with low electrical energy rates and high fossil fuel costs. Several of the existing projects have involved canneries or seafood processing plants where natural gas is not available and oil is used for process heat or wash-down water. Electrical energy savings are both site and process-specific and relate to decreased use of circulating water pumps, condenser fans, and combustion air fans relative to heat pump compressor, fan, and pumping requirements. While the heat delivered may far exceed the Btu content of the electrical energy consumed, this may be viewed as a fuel switching technology.
Emerson, 2014. Industrial Heat Pumps Emerson Climate Technologies
Douglas Reindl, et. al., 08/01/2007. Heat Recovery in Industrial Refrigeration ASHRAE Journal
Donall O’Brien, 2010. Industrial Heat Recovery: Featuring Refrigeration Heat Recovery Case Study (Power Point Presentation) Industrial Utilities LTD (Ireland)
Emerson, 2010. Single Screw Ammonia Heat Pumps Emerson Climate Technologies (Europe)