Abstract: A method for controlling a plurality of electronic switches employed to connect an alternating current voltage source with a motor. The method comprises the steps of generating a signal, directing the signal to each of a series of output lines in sequence, regularly repeating the directing step, conducting the signal from the output lines to the electronic switches to actuate the electronic switches, and continuously resynchronizing the directing of the signal with the voltage cycle of the voltage source.

Abstract: A heat exchanger bypass system for an absorption refrigeration system is disclosed. The bypass system operates to pass strong solution from the generator around the heat exchanger to the absorber of the absorption refrigeration system when strong solution builds up in the generator above a selected level indicative of solidification of strong solution in the heat exchanger or other such blockage. The bypass system includes a bypass line with a gooseneck located in the generator for controlling flow of strong solution into the bypass line and for preventing refrigerant vapor in the generator from entering the bypass line during normal operation of the refrigeration system. Also, the bypass line includes a trap section filled with liquid for providing a barrier to maintain the normal pressure difference between the generator and the absorber even when the gooseneck of the bypass line is exposed to refrigerant vapor in the generator.

Abstract: A triple loop heat exchanger for an absorption refrigeration system is disclosed. The triple loop heat exchanger comprises portions of a strong solution line for conducting relatively hot, strong solution from a generator to a solution heat exchanger of the absorption refrigeration system, conduit means for conducting relatively cool, weak solution from the solution heat exchanger to the generator, and a bypass system for conducting strong solution from the generator around the strong solution line and around the solution heat exchanger to an absorber of the refrigeration system when strong solution builds up in the generator to an undesirable level.

Abstract: Apparatus and a method for providing failsafe supplemental heat operation of an air conditioning control are disclosed. Operating power to a microprocessor control is discontinued when the air conditioning unit is placed in a supplemental heat mode by the user. The microprocessor control is so arranged that appropriate connections are made to operate a supplemental heat source in response to a first stage heating need being sensed by the thermostat when operating power to the microprocessor control is discontinued. Under normal conditions multiple stage heating operation is provided with a supplemental heat source being operated under control of a programmed microprocessor.

Abstract: A noise reducing heat exchanger assembly for a combustion system is disclosed. The heat exchanger assembly includes a plurality of side by side heat exchangers each having a single inlet for an inshot burner. An auxiliary port is located just above each burner inlet. A coupling chamber may be used to interconnect the auxiliary ports to allow acoustical coupling between the heat exchangers and to substantially prevent potential fluid flow between the heat exchangers and the surroundings of the combustion system. This heat exchanger assembly is particularly suitable for use as part of an induced draft combustion furnace.

Abstract: A vapor compression refrigeration system with a tube in shell subcooler for use in low temperature cooling applications such as in a brine chilling application is disclosed. The subcooler has a drain system for draining liquid refrigerant from the shell side of the subcooler at shutdown of the refrigeration system to prevent undesirable amounts of water from freezing in the tubes of the subcooler after shutdown of the refrigeration system.

Abstract: Method and apparatus are disclosed wherein a circuit for detecting the phase angle of a motor is disclosed. This circuit utilizes zero crossing detectors to compare the voltage and current signals such that a digital signal indicating the value of the phase angle by the duration of the signal is generated. Additionally, a method and apparatus for comparing the phase angle to the reference phase angle value is disclosed. Means for updating the reference value and for comparing the detected value to the reference value to determine appropriate defrost initiation time are additionally disclosed.

Abstract: An apparatus and method are described for integrating the operation of a fossil fuel fired furnace with a heat pump. A microprocessor control is utilized to regulate the operation of the furnace such that should the compressor of the heat pump be operating even in a malfunction condition the fossil fuel fired furnace may not be energized. The logic further provides for the compressor being de-energized should the fossil fuel fired furnace be operated.

Abstract: An apparatus and method is disclosed for regulating delay periods in the operation of an air conditioning system. A speedup means is provided for a serviceman to speed up the delay intervals to avoid long waiting periods between modes of operation of the air conditioning unit. Means are provided for removing the speedup means after delay periods have occurred to prevent inadvertent operation of the air conditioning system with shortened delay intervals.

Abstract: An air-cooled, vertical tube absorber for an absorption refrigeration system is disclosed. Strong absorbent solution is supplied to the top of the absorber and refrigerant vapor is supplied to the bottom of the absorber to create a direct counterflow of refrigerant vapor and absorbent solution in the absorber. The refrigeration system is designed so that the volume flow rate of refrigerant vapor in the tubes of the absorber is sufficient to create a substantially direct counterflow along the entire length of each tube in the absorber. This provides several advantages for the absorber such as higher efficiency and improved heat transfer characteristics, and allows improved purging of non-condensibles from the absorber.

Abstract: A high efficiency induced draft clamshell type heat exchanger for use in a hot air furnace. The geometry of the heat exchanger is such that the various segments are compactly arranged to transfer heat from the fuel to the air passing over the heat exchanger surface while maintaining the discharged products of combustion at a temperature sufficiently high to prevent condensation from forming or collecting within the heat exchanger during steady state operation.

Abstract: A centrifugal vapor compressor having a two-position, pressure controlled diffuser throttle ring is disclosed. The throttle ring is positively maintained in a minimum or a maximum throttling position by supplying either a relatively low pressure or a relatively high pressure, respectively, to a cavity behind the throttle ring. The throttle ring may be one of any of a variety or types of throttle rings including a new, improved throttle ring having a back portion with a sealing means which facilitates sliding movements of the throttle ring and which prevents vapor flow between the cavity behind the throttle ring and the diffuser passageway.

Abstract: Methods for determining rate of fuel flow to a combustion engine is disclosed. The fuel flow rate determination is made by measuring a pertubation in air-to-fuel-flow ratio to the engine, or in the volumetric concentration of a gaseous test species in the exhaust, after adding a known amount of a test substance to the air flow intake to the engine, or to the exhaust from the engine, respectively. The desired fuel flow rate is calculated from the measured parameters.

Abstract: A probe for measuring electrical conductance to determine water concentration in a fluid is disclosed. The probe comprises a pair of spaced apart electrodes and a bridge of protein gel between the electrodes. The probe is especially useful for monitoring water concentration in the lubrication oil for a compressor drive train of a hermetic vapor compression refrigeration system. In such a refrigeration system the water concentration in the lubrication oil corresponds to water concentration in the refrigerant of the refrigeration system.

Abstract: A dilution cycle control system for an absorption refrigeration system is disclosed. The control system includes a time delay relay for sensing shutdown of the absorption refrigeration system and for generating a control signal only after expiration of a preselected time period measured from the sensed shutdown of the absorption refrigeration system, during which the absorption refrigeration system is not restarted. A dilution cycle for the absorption refrigeration system is initiated in response to generation of a control signal by the time delay relay. This control system is particularly suitable for use with an absorption refrigeration system which is frequently cycled on and off since the time delay provided by the control system prevents needless dilution of the absorption refrigeration system when the system is turned off for only a short period of time and then is turned back on.

Abstract: A pressure differential gage and a method for detecting the presence of noncondensible gases in a refrigeration system. The pressure differential gage comprises a housing, a diaphragm, first and second tubes, a reference fluid, and indicator means. The diaphragm separates the housing into first and second chambers. The first tube has one end in fluid communication with the first chamber and a second end open to receive a sample vapor, which determines the pressure in the first chamber. The second tube has one end in fluid communication with the second chamber and a closed second end. The reference fluid is located in the second tube and determines the pressure in the second chamber. The indicator means is actuated by the diaphragm to indicate when the pressure in the first chamber differs from the pressure in the second chamber.

Abstract: An optical position sensor for monitoring displacements of a movable body is disclosed. The sensor includes a light source transmitter, a light sensing receiver, a digital switching device, and a special encoder plate attached to a movable body. The encoder plate has rows of apertures which are constructed to modulate the light signal transmitted between the transmitter and receiver as a function of plate position to provide a symmetrical digital output signal when the switching device is triggered at a preset practical minimum threshhold level. Fiber optics are particularly suitable for use in constructing such an optical position sensor.

Abstract: A high performance heat transfer tube for use in an evaporator of a refrigeration system is disclosed. The tube has at least one helically extending fin convolution on its external surface and at least one helically extending rib on its internal surface. The fin convolution has bent over tip portions which touch the adjacent convolution to form subsurface passages at those sections of the fin convolution which are not located above an internal rib. Depressed sections of the fin convolution located above an internal rib have bent over tip portions which do not touch the adjacent convolution to form cavities. The subsurface passages and cavities form a subsurface channel having fluid communication with the surroundings of the tube through the cavity openings.

Abstract: A heat exchanger assembly for a refrigeration system is disclosed. The assembly is a single vessel construction having an evaporator, condenser and flash subcooler. A plate inside the shell separates the evaporator from the condenser and the flash subcooler, and a partition inside the vessel separates the condenser from the flash subcooler. Removable orifice means in the partition control flow of refrigerant into the subcooler from the condenser. Removable solid pipe plugs in the shell of the vessel provide access to the orifice means so that, if desired, an individual orifice means may be removed and replaced with another, different sized orifice means.

Abstract: A method of testing oil for ionic contaminants is disclosed. The method comprises isolating a sample of the oil to be tested and mixing it with an equal weight of distilled water to dissolve ionic contaminants in the oil sample into the distilled water. Then, the contaminated water is separated from the mixture and its conductivity is determined. An alternative to separating the contaminated water is to use a surfactant to form an oil in water emulsion with the oil sample and the distilled water. The conductivity of the emulsion is determined directly. The magnitude of the conductivity directly indicates the amount of ionic contaminants present in the oil being tested. This method is especially suitable for determining the level of ionic contamination in the refrigerant of a refrigeration system of the type having a compressor drive which is lubricated with oil and wherein there is contact between the refrigerant and the oil.