Abstract: An electronic expansion valve (EEV) is operated by a motor controlling a variable restriction valve in which a liquid refrigerant enters at a high pressure and exits at a reduced pressure. The motor controls the depth of a tapered needle which, as extended, penetrates multiple fixed orifices, aligned in series. Additional fixed orifices, downstream of the fully extended needle, provide further restriction and management of refrigerant flashing. Depending on the desired operating range, the following elements may be controlled: needle length, diameter, and taper; diameter, thickness, and relative elevation of each orifice; response and maximum torque provided by the motor; and geometry of the valve enclosed volume.

Abstract: A method operates an absorption heat pump system, specifically the flow of hydronic cooling fluid through the condenser during system start-ups, or when the cooling fluid temperature is low. To minimize the time for an absorption heat pump to reach full cooling or heating capacity, it is desirable for the high side pressure to increase as fast as possible, and the low side pressure to decrease as fast as possible. Since the high side pressure is a function of the temperature of the refrigerant exiting the condenser, if the condenser cooling fluid temperature is low, the corresponding high side pressure will be low, which may not permit adequate working fluid flow rates from the high pressure side of the system to the low pressure side.

Abstract: An electronic expansion valve (EEV) is operated by a motor controlling a variable restriction valve in which a liquid refrigerant enters at a high pressure and exits at a reduced pressure. The motor controls the depth of a tapered needle which, as extended, penetrates multiple fixed orifices, aligned in series. Additional fixed orifices, downstream of the fully extended needle, provide further restriction and management of refrigerant flashing. Depending on the desired operating range, the following elements may be controlled: needle length, diameter, and taper; diameter, thickness, and relative elevation of each orifice; response and maximum torque provided by the motor; and geometry of the valve enclosed volume.

Abstract: A method operates an absorption heat pump system, specifically the flow of hydronic cooling fluid through the condenser during system start-ups, or when the cooling fluid temperature is low. To minimize the time for an absorption heat pump to reach full cooling or heating capacity, it is desirable for the high side pressure to increase as fast as possible, and the low side pressure to decrease as fast as possible. Since the high side pressure is a function of the temperature of the refrigerant exiting the condenser, if the condensor cooling fluid temperature is low, the corresponding high side pressure will be low, which may not permit adequate working fluid flow rates from the high pressure side of the system to the low pressure side.

Abstract: A waste heat source (100) is used to heat a high temperature heat transfer fluid which is used to heat an absorption heat transfer machine (10) having a generator (20), an absorber (30), a condenser (40), and an evaporator (50) operatively connected together. The high temperature heat transfer fluid can also be used to heat a load (190) such as a room space or a process. The waste heat source (100) can also be used to heat an intermediate heat transfer fluid, which can be used to heat a second load (175) such as a space, a process, or an absorption heat transfer machine. Novel flow control devices (70, 60) for controlling the flow of weak solution from generator (20) to absorber (30) or of refrigerant from condenser (40) to evaporator (50), respectively, are also described.