SMTI has leveraged its expertise in absorption heat pumps (AHP) to develop a highly scalable low cost system that outperforms conventional heating systems and electric heat pumps. This is accomplished with the single-effect AHP cycle which limits complexity and enables high levels of performance over all operating conditions.
The AHP cycle is heat source flexible and can be driven by a range of heat sources including Solar Thermal (ST), Waste Heat (WH) such as engine exhaust, Natural Gas (NG), Propane (PG), and Liquid Fuels (LF) such as Fuel Oil and Bio Diesel.
The AHP is also heat sink flexible and can provide heat for a range of applications including Residential Water Heater (RWH), Residential Space Heating (RSH), Residential Combi (RCOMBI), Commercial Water Heating (CWH) and Commercial Water Heating/Space Cooling (CWH/SC).
The single-effect absorption heat pump (AHP) maximizes internal heat recovery unlike more basic AHP configurations while minimizing complexity experienced by more advanced cycles. This balance allows the system to operate at high efficiencies and still be cost effective.
In an absorption heat pump, high temperature (>300°F) heat is used to generate refrigerant in the Desorber. The generated refrigerant is purified in the Rectifier and flows through the standard refrigeration loop (Condenser, expansion device, and Evaporator). Medium temperature heat (100 to 160°F) is removed from the system in the Condenser. Low temperature heat (-20 to 95+°F) is added to the system in the Evaporator. The refrigerant exits this loop and combines with the solution that it was originally boiled out of in an exothermic process. This medium temperature (100 to 160°F) heat is removed from the system in the Absorber. Internal heat recovery is performed in the Solution and Refrigerant Heat Exchangers.
In the system developed by SMTI, a combustion system is coupled to the Absorption Heat Pump and acts as the high temperature source. The high temperature source accounts for 1 unit of energy into the system. The Evaporator exchanges heat directly with the surrounding ambient, which acts as the low temperature source and provides another 0.15 - 0.7 units of energy into the system, depending on ambient temperature. The Absorber and Condenser of the system are hydronically coupled to a an intermediate water loop which provides the desired heating. By ‘pumping’ low temperature heat from the ambient, the system is able to provide 1.15 - 1.7 units of heat for every 1 unit of high temperature thermal energy used.
A condensing Flue Gas Heat Exchanger is added to AHP to capture additional heat from the flue gas stream and provide an additional 0.05 to 0.15 units of heat to the intermediate water loop.