The engineers conducted tests under a three-way Cooperative Research and Development Agreement between the US Army Engineer Research & Development Center's Construction Engineering Research Laboratory (ERDC-CERL), Concurrent Technologies Corporation and FuelCell Energy.
FuelCell Energy supplied one of its Direct FuelCell (DFC) power plants, which was used in conjunction with an absorption chiller, which converts heat waste into chilled water for air conditioning.
FuelCell Energy said successful completion of the air conditioning application tests added value to its fuel cell technology, which had already demonstrated its capacity for creating clean energy and heat for buildings.
"Using the heat to chill water for air conditioning can provide better economics for cogeneration, especially in markets with high electricity costs and warmer climates," said FuelCell Energy.
The tests were conducted with a 250kW DFC300A power plant and a 20 ton absorption chiller with a 17.9 ton cooling capacity, estimated on fuel cell exhaust, manufactured by Broad.
Over the 1200 hours of testing, the absorption chiller substantially exceeded its rated capacity of 17.9 tons – generating a maximum of 19.5 tons of cooling – when using the fuel cell's heat exhaust as its energy source, according to FuelCell Energy.
"Integrating and optimising a chiller with a fuel cell in many cases will afford higher overall efficiencies and better utilisation of the fuel cell's waste heat," said the CERL fuel cell team project leader, Franklin Holcomb.
"This can be a very strong economic driver for Department of Defense installations that have long cooling seasons, or for specific building applications – such as hospitals, which require continuous cooling," Holcomb said.
This year the Defense Department installed a similar gas-powered system at Fort Bragg in North Carolina, its largest army base.
The Fort Bragg prototype cooling, heating and power (CHP) generation system uses a 5MW gas-turbine to achieve up to 70% overall energy efficiency by recycling waste heat energy to provide heating and cooling that would otherwise be powered from the turbine's electrical output.
