Tri-generation energy system technology (TRIEST)

Steam jet refrigeration for micoturbine-based CHP with watertube or firetube boiler heat recovery.

Altex Technologies Corporation


San Jose, CA

Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Project Result

The project was completed in August, 2014 and the final report is available on the Energy Commission website. Publication number: CEC-500-2015-026

The Issue

Short payback times for microturbine-based CHP systems depend on round-the-clock utilization of the full electric output and exhaust heat recovery. Many potential applications have seasonably variable heat loads and are unable to take full advantage of heat recovery in absence of a viable use for the excess heat. However, many of these same facilities will have cooling loads that can be serviced by the excess heat if low cost equipment is available to convert steam from heat recovery into refrigeration.

Project Innovation

Altex designed and demonstrated a 6 ton (cooling) prototype steam jet refrigeration system capable of producing chilled water from process steam generated by the boiler used to recover exhaust heat from a microturbine-generator CHP system. The advantage of this technique over other heat-to-refrigeration systems, such as absorption chillers, is that it is less expensive, utilizes less floor space, and maximizes the use of an extant heat recovery apparatus. In addition, no hydrofluorocarbons, chlorofluorocarbons, or other volatile organics are utilized. The coefficient of performance was generally low, as expected (about 0.32), but is of little concern when the cost of steam production is low. The electricity cost of this process was found to be 50-60% of conventional vapor-compression refrigeration, and the working temperatures were found to be similar.

Project Benefits

The chief benefit of steam jet technology applied to microturbine-based CHP with heat recovery via a conventional gas-fired boiler is that it makes CHP more attractive in cases where year-round steam loads are not sufficient to fully utilize the waste heat from the microturbine.

Lower Costs


Researchers estimate that the payback time is less than three years in cases where waste heat utilization would otherwise be less than about 75 percent.



Leva Energy, Incorporated


Match Partners


Altex Technologies Corporation


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