Showing papers on "Thermal expansion valve published in 1988"

Bellows heat pipe for thermal control of electronic components

Abstract: A bellows type heat pipe which conducts heat away from an electronic device to a heat sink. The heat pipe is a sealed bellows type container which has an evaporator section at one end and a condenser section at an opposite end. The evaporator section contains a saturated radial wick while the condenser section is lined with a radial wick and a circumferential wick. A corrugated slab wick is longitudinally disposed within the heat pipe interconnecting the evaporator and the condenser sections. The evaporator section is placed on the electronic device and the condenser section is enclosed in a housing which is connected to a heat sink. In operation, the electronic device generates heat energy which causes the fluid in the evaporator to vaporize building a vapor pressure in the heat pipe. The heat pipe expands in the direction of the condenser causing the condenser section to make intimate contact with the inside of the housing. The vapors condense at the condenser section and are brought back to the evaporator section via the circumferential wick, the walls of the bellows vessel and the wick slab.

Indicating refrigerant liquid saturation point

Abstract: A refrigerant control system employing a "self-heated" thermistor disposed in the high pressure refrigerant line to sense refrigerant temperature from the condenser as it enters the expansion valve or capillary. The voltage drop is detected across a resistor in series with the thermistor and converted to saturation pressure from known refrigerant properties. A microprocessor de-energizes the compressor and turns on the condenser fan when excessive saturation pressure is detected. An optional second thermistor senses actual refrigerant temperature for comparison with the saturation temperature to determine sub-cooling and the microprocessor disables the compressor in the event of excessive or insufficient sub-cooling.

Refrigeration cycle control apparatus

Abstract: A refrigeration cycle or an air conditioner including a refrigeration cycle is subjected to feedback control based on modern control theory. An apparatus controlling a controlled object, that is, the refrigeration cycle of the air conditioner including the refrigeration cycle, is formed as an optimal regulator. A controlled input to the controlled object includes a capacity of a compressor or a degree of opening of an expansion valve. A control output from the controlled object includes a temperature of air at a point downstream of the evaporator or a superheat of refrigerant. Feedback gains are predetermined by use of dynamic models constructed for respective steady operation states of the controlled object.

Solenoid valve with supply voltage variation compensation

Abstract: A solenoid valve used as an expansion valve in a refrigeration circuit has an opening that varies as a function of the pulse width of a high frequency PWM (pulse width modulated) control signal. A transistor controls the electrical current delivered to the solenoid valve. The PWM control signal rapidly cycles the transistor on and off at a constant frequency that is sufficiently high to prevent the valve from having enough time within a cycle to move between fully open and closed. As a result, the valve balances at an intermediate position determined by the relative lengths of the on and off periods of each pulse cycle. The relative on-off pulse widths, often referred to as, "duty cycle", is varied in response to a temperature sensor to control the flow of refrigerant through the refrigeration circuit. The duty cycle is also adjusted to compensate for any variations in the supploy voltage applied across the solenoid valve.

Controlling superheat in a refrigeration system

Abstract: A vapor compression refrigeration system is which a self heated thermistor is located in the suction line downstream of the evaporator to directly sense the quality of the refrigerant flowing thereover Appropriate circuitry measures the voltage drop across the thermistor and this drop is used to vary the duty cycle of the system's expansion valve thereby controlling the superheat of the evaporator

Adaptive refrigerant control algorithm

Abstract: A refrigeration system comprises a compressor, a condenser, an evaporator, an accumulator, and an adjustable controllable expansion valve. An electronic control system monitors the value of superheat and accordingly provides an electrical control signal to adjust the controllable expansion valve in order to maintain a set point superheat value. An unfiltered path is provided to ensure expedient response when the system starts operation and when dynamic changes occur. A filtered path is provided to reduce hunting, or oscillations about the set point, of the superheat value during steady state operation.

Pulse controlled expansion valve for multiple evaporators and method of controlling same

Abstract: A pulse controlled refrigeration expansion valve for multiple evaporators and method of controlling the valve is disclosed. The refrigeration system on which this invention is typically used includes a single source of pressurized refrigerant and a plurality of .[.evaportors.]. .Iadd.evaporators.Iaddend.. Each evaporator has an expansion valve associated therewith which is preferably an on/off (open/closed) direct controlled solenoid valve. The valve is periodically energized (opened) and de-energized (closed) in response to a parameter (e.g., superheat) of its respective evaporator such that the ratio of energization time/de-energization time during each period (e.g., 4 seconds) of operation of the valve is varied in response to the system parameter(s) and such that the on/off solenoid valve functions as a modulated refrigerant flow control expansion valve. A temperature sensor is provided which senses the temperature of the space being refrigerated by a respective evaporator (e.g., the interior of a freezer cabinet in a supermarket) so that upon the temperature of the refrigerated space controlled by the respective valve being within a predetermined temperature range, the temperature sensor will override the control for the solenoid valve thus closing the valve and stopping the flow of refrigerant through the respective evaporator while refrigerant continues to flow to other evaporators.

Refrigeration control system for cold drink dispenser

Abstract: A cold drink dispenser and, more particularly a refrigeration system for such a dispenser, is disclosed The dispenser has a beverage flow path, a first coil or evaporator for prechilling a beverage flowing through the beverage flowpath, and a second or ice bank coil immersed in a liquid bath with the flowpath also immersed in the ice bath A first modulatable expansion valve (eg, a pulse modulated solenoid valve) is used to regulate the flow of refrigerant through the first coil and a second modulatable valve is used to regulate the flow of refrigerant through the ice bank coil A control system (eg, a microprocessor-based control) monitors certain temperatures and initiates or blocks the flow of refrigerant through one or both of the coils in response to certain pre-established system paramaters so as to insure that the beverage dispensed is below a desired temperature, even under high load operating conditions

Dual evaporator air conditioner

Abstract: This application concerns an automobile air conditioning system having two evaporators and one compressor which is alternately activated and deactivated to prevent frost from accumulating on one of the evaporators by way of a refrigerant pressure responsive switch at the outlet of the one evaporator. A one-way check valve is located near the switch and between the evaporators to prevent reverse flowing of refrigerant from the one evaporator to the other evaporator.

Heat-pipe system and method of and apparatus for controlling a flow rate of a working fluid in a liquid pipe of the heat pipe system

Abstract: A heat-pipe system of the two-phase fluid loop type comprising a liquid duct as a main loop for circulating a working fluid in liquid phase by a pump, an evaporator having a first capillary structure to which the working fluid is supplied from high pressure side of the main loop, a condenser having a second capillary structure for returning liquid condensate to the low pressure side of the man loop after radiating heat in the condenser, and a bypass pipe connected between the evaporator and the radiator for transporting vapor evaporated in the evaporator through its capillary structure to the second capillary of the condenser. With this construction, since the working fluid is circulated by the pump while the supply of the liquid corresponding to that evaporated in the capillary structure of the evaporator is carried out by the capillary force in the evaporator, a large amount of heat can be transported over long distances. A method of and apparatus for controlling a flow rate of a working fluid in a liquid duct of the heat-pipe system is also disclosed.

Method of operating a once-through steam generator

Abstract: A method of operating a once-through steam generator having a first evaporator heating surface formed of a tube wall of a combustion chamber, and a second evaporator heating surface connected in parallel to the first evaporator heating surface at a water inlet side thereof, the second evaporator heating surface being located in a convection chamber post-connected to the combustion chamber at a flue-gas outlet side thereof downstream from a superheating surface as viewed in a flow direction of flue gas, includes opening a water regulating valve preconnected to the second evaporator heating surface in the flow direction of the feedwater, if a predetermined value of a mass flow of the feedwater into the once-through stem generator is exceeded, so as to initiate a partial mass flow of the feedwater into the second evaporator heating surface; and closing the water regulating valve again, if the predetermined value fails to be attained, so as to terminate the partial mass flow of the feedwater into the second evaporator heating surface.

Air-conditioning system on a motor vehicle

Abstract: The invention relates to an air-conditioning system (1) on a motor vehicle with a working medium circuit, in which there are fitted in series, according to the flow direction of the working medium, a compressor (2), a first heat exchanger (4), an expansion valve (7) and a second heat exchanger (6) in the air inlet (17) into the interior of the vehicle. According to the invention, there is additionally provided a second working medium circuit as a heat-pump circuit. For this purpose, downstream from the compressor (2) there is a switchable working medium line (16) connected directly to the inlet of the second heat exchanger (6), bypassing the first heat exchanger (4) and the first expansion valve (7). Furthermore, the direct line (9) between the second heat exchanger (6) and the compressor (2) can be shut off (solenoid valve 11). Bypassing this line (9), there leads to the compressor (2) a line (12) in which there lies a second expansion valve (13) and, behind it, a third heat exchanger (14). This heat exchanger (14) is flowed through by the coolant of the internal-combustion engine (arrows 15). In heat-pump operation (cycle as in the drawing), the second heat exchanger (6) acts as a condenser and the third heat exchanger (14) acts as an evaporator.

Falling film evaporator

Abstract: This invention relates to a falling film evaporator which is arranged to cause a liquid film to flow downward to thereby effect heat exchange using evaporation. In a space of an evaporating compartment (31), a gas-liquid separator (22) is disposed to communi­cate with a compressor (11) which constitutes a part of a refrigeration cycle.

Superheat control of air conditioning system incorporating fuel cooler

Abstract: A system for preventing vapor-lock in a positively pressurized loop-type engine fuel line having the low pressure or tank return portion of the fuel line passing through a heat exchanger disposed in the refrigerant line for the vehicle air conditioner between the endothermic heat exchanger or evaporator and the compressor inlet. A thermistor senses the temperature of the refrigerant discharging from the fuel line heat exchanger and a pressure transducer senses evaporator discharge saturation pressure. Look-up tables are used to determine saturation temperature from the saturation pressure, and saturation temperature and actual refrigerant temperature compared to generate a pulse-width modulated control signal for controlling an electrically operated refrigerant expansion valve to maintain a desired amount of superheat at the discharge of the fuel line heat exchanger.

Device for controlling capacity of variable capacity compressor

Abstract: A control device for a compressor in an automotive air conditioning system is disclosed which includes a pressure sensor disposed on a conduit concerning an evaporator and the compressor for detecting a refrigerant pressure at an outlet side of the evaporator. A control unit compares a pressure change ratio based on the detected refrigerant pressures with a predetermined pressure change ratio and selects either one of two ranges of predetermined values in accordance with the compared results, and further compares the refrigerant pressure with the predetermined values, thereby controlling the operation of an electromagnetic clutch which is mounted on the compressor and the capacity of the compressor in accordance with the last mentioned compared results.

Refrigeration sub-cooler

Abstract: A sub-cooler for a refrigeration system is located between the condenser and the expansion device for the evaporator. The sub-cooler has a sealed cylindrical housing with a main inlet coupled to the outlet of the condenser. This inlet is connected to a spray bar located along the length of the housing near its top, and spray apertures are distributed along the length of the spray bar to spray the refrigerant into the interior of the sub-cooler housing. The temperature controlled expansion valve supplies a tapped off portion of the refrigerant from the condenser to a distributor located within the housing. Three to six separate cooling coils, having multiple turns, extend from the distributor throughout the interior of the housing. The other ends of the cooling coils are coupled with a collector in the housing, and the outlet from the collector is injected into the main suction line coupled to the inlet of the compressor. An outlet is connected to the bottom of the sub-cooler housing for supplying refrigerant to the expansion valve for the evaporator. Refrigerant is sub-cooled a few degrees within the sub-cooler; and, in addition, gas bubbles are removed from the refrigerant supplied to the primary expansion device for the system.

Refrigeration system and method involving high efficiency hot gas defrost of plural evaporators

Abstract: A hot gas defrost type refrigeration system in which refrigerant used to defrost is returned to the system's refrigerant circuit after being collected and reduced in pressure, as by expansion valve means (180), to a pressure below the pressure in the system's return suction header (56), then heated as by means (132) involving heat exchange with the system's high pressure refrigerant, the refrigerant used to defrost thus being in a superheated gaseous state and returned to the system's return suction header (56) in such state without risk of introduction of liquid refrigerant to the system's compressor(s) (C1, C2, C3).

Quench expansion valve refrigeration circuit

Abstract: A refrigeration circuit (10) is provided with a guench line (30) connecting the liquid line (18) and the suction line (26) and containing a quench expansion valve (32). The quench expansion valve (32) is controlled responsive to the superheat of the refrigerant supplied to the compressor (12). By injecting liquid refrigerant downstream of the suction modulation valve (28) and the sensor for the thermal expansion valve (20), the system can be operated at low capacity without overheating the compressor oil.

Refrigeration system including refrigerant noise suppression

Abstract: A refrigeration system comprising in closed series-flow relationship, a condenser, a capillary tube flow restrictor, and an evaporator including means connecting the outlet end of the restrictor to the evaporator inlet for reducing the noise generated by refrigerant flowing from the restrictor.

Cooling apparatus and control method

Abstract: A cooling apparatus includes a bypass provided to a path (36) extending from a compressor (21) to an expansion valve (23) via a condenser (22), and a unit (25) for controlling a ratio of a flow rate of a refrigerant of the path via the condenser (22) to that of the bypass path (36), or a unit (27) for varying an air volume of a fan of an outdoor unit for blowing the condenser (22) so as to vary a capacity of the condenser (22). The degree of superheat of the refrigerant is measured at an exit of the evaporator (24), and an expansion valve (23) is controlled in accordance with the measured degree of superheat.

The effect of oil on the performance of heat pumps and refrigerators—II. Experimental results

Abstract: The results of a prolonged investigation of the influence of the lubricating oil Shell Clavus 68 on the performance of an R12-based refrigeration-heat pump system are presented. The strategy is discussed for deciding if a given series of data collected at 10s intervals adequately represents the chosen experimental conditions and results are presented under both transient and steady state conditions. The effects of oil on evaporator capacity, coefficient of performance, heat transfer rates, evaporator outlet superheat stability, refrigerant mass flow rate, evaporator pressure drop and compressor discharge temperature are discussed, and the experimental results are compared with a theoretical analysis. Finally, it is shown that under certain (albeit unlikely) conditions, it is possible for both the evaporator and condensor to act as heat rejectors.

Automotive air-conditioning system and apparatus

Abstract: An apparatus for the air-conditioning of the interior of automobiles, with a refrigerant circuit, including a low-pressure part and a high-pressure part and in which vaporous refrigerant is drawn off from the evaporator by a compressor and, while experiencing an increase in pressure, the refrigerant is fed to a condenser for cooling and condensation. The condensed refrigerant is collected in a collecting vessel from which it can be diverted via an expansion valve into the evaporator while experiencing a pressure drop and cooling. A pressure-relief valve witha blow-out outlet is proided between the compressor and the condenser in the high-pressure part of the refrigerant circuit. The blow-out outlet of the pressure-relief valve is connected to an intermediate reservoir for the escaping refrigerant.

Heat exchanging system for power generation

Abstract: This is a heat exchanger having a heating cycle part and a thermal cycle part. The heating cycle part comprises a compressor which is driven by the thermal power cycle in a heating medium circulation line connecting a radiator and an evaporator while the thermal power cycle part includes a turbo-engine in the thermal power medium circulation line connecting a condenser and an evaporator. The output shaft of the turbo-engine is connected to the compressor, and a heater as a constant heat source is provided for heating the evaporator in the thermal power medium circulation line. If the compressor is replaced with a power generator, the heat exchanger can be used as a power generator/heat exchanger of temperature-difference-driven type. The components are housed in a pressure vessel to thereby simplify the structure without necessity for a special pressure resistance structure.

Method and device for control of an air conditioning system for vehicles

Abstract: A method of controlling a motor vehicle air conditioning system is described. The motor vehicle air conditioning system comprises a refrigeration circuit with a coolant compressor (43), a condenser (16, 51), an evaporator (21, 22) and a restriction device (23, 24) located upstream of the evaporator (21, 22). A fan is assigned to the condenser (16, 51) and a blower (58) to the evaporator (21, 22). The compressor output, the condenser output and the evaporator output are detected directly or indirectly by sensors (52, 53) and fed as electrical variables to an electronic control circuit (1) which combines these input signals and generates output signals as a function of at least two of these output values and incorporating other parameters. The control circuit (1) acts on electrically controllable control elements (10, 11, 65, 66, 23, 24) to influence the compressor output, the condensor output and/or the evaporator output.

A theoretical analysis of a solar-fuel assisted absorption power cycle (SFAPC)

Abstract: This study presents a novel power generating cycle suitable for solar energy applications. A modified version of the conventional LiBr-H2O absorption refrigerating machine is used for the proposed cycle. The condenser, expansion valve and evaporator are replaced by a superheater and a steam turbine, while a flashing tank replaces the generator. The cycle is powered by medium concentrators with a solar collecting temperature of 165°C. Steam generated in the flashing tank (100 kPa) is superheated (using fuel) to 600°C before it expands in the turbine down to 1.25 kPa. This is maintained by the equilibrium conditions in a water cooled absorber, LiBr-H2O solution is directly circulated in the solar collectors and the non-solar energy input to the system is 23% of its total requirements. Results showed that using a 710 ton refrigeration absorption machine, the SFAPC would generate 960 kW shaft power at a system thermal efficiency of 25% which is 44% higher than the available systems. Moreover, when the SFAPC is combined with a vapour compression refrigerator, an overall COP of 1.4 is obtained. This is 72% higher than that of the absorption machine alone at the expense of 23% non-solar energy supply.

Multichamber type air conditioner

Abstract: PURPOSE: To remarkably improve general purpose properties, by a method wherein control of a capacity of two compressors is effected according to a pressure on the low pressure side during cooling and a pressure on the high pressure side during heating and in response to a total of the air conditioning loads of an indoor machine, and the opening of an indoor motor expansion valve is controlled according to the air-conditioning load of the indoor machine. CONSTITUTION: A capacity of a capacity varying compressor 31 and that of a pole varying type compressor 33 are controlled according to a pressure detected by a pressure detector 41. During cooling, a pressure on the low pressure side is detected, and control is effected so that a pressure is decreased to a given set low value. During heating, a pressure on the high pressure side is detected, and control is made so that a pressure is increased to a given high value. A difference between a detecting pressure and a set pressure is calculated by a pressure difference means 55. An inverter 32 and a number of poles switching device 34 are controlled by a capacity varying width deciding and control means 56 which changes a predetermined combination step for control combination of two types of capacity of two compressors 31 and 33. COPYRIGHT: (C)1989,JPO&Japio

Method for evaporation of liquids

Abstract: Process for the evaporative concentration of liquids. Vaporization is carried out by indirect heat exchange with a heating fluid in an evaporator. The vapor produced in the evaporator is thereafter condensed in a condenser by indirect heat exchange with a cooling liquid which is mainly composed of the liquid to be concentrated or the liquid which has already been concentrated in the evaporator. The vapor pressure over the cooling liquid in the condenser may be lowered by causing gas to flow in contact with the cooling liquid.

Air conditioning process and apparatus therefor

Abstract: An air conditioning process and apparatus includes absorption of water vapor in a circulating absorption liquid composed of an aqueous salt solution. The absorption liquid is regenerated by evaporative concentration by indirect heat exchange with a heating fluid in an evaporator. The water vapor produced in the evaporator is condensed in a condenser by indirect heat exchange with a cooling liquid which is mainly composed of the absorption liquid to be concentrated or which has already been concentrated in the evaporator. The water vapor pressure over the cooling liquid in the condenser is lowered by causing gas to flow in contact with the cooling liquid.

Electromotive expansion valve

Abstract: PURPOSE:To carry out the control of a large flow in a compact size valve by furnishing a valve body engaging device to enable the movement of a valve body after an auxiliary valve body is separated sufficiently from an auxiliary valve seat. CONSTITUTION:A valve body 4 is formed to be able to make a valve rod 6 penetrate from a back pressure chamber 15 side up to an auxiliary valve chamber 42, and a needle-formed auxiliary valve body 61 furnished at the top of the valve rod 6 is opposed to an auxiliary valve seat 44 so as to compose an auxiliary valve. A gap between the valve body 4 and the valve rod 6 is sealed up slidable each other by a packing 8. When a valve rod 6 is retreated a little, only the opening of the auxiliary valve is increased proportionally responding to the movement of the valve rod 6. When the valve rod 6 is retreated further and after a stopper 62 contacts a packing gland 45, the valve body 4 moves together with the valve rod 6 in the condition where the valve body 4 is engaged with the valve rod 6.