Showing papers on "Heat exchanger published in 1987"

Plate heat exchanger

Abstract: A plate heat exchanger realizing improved heat exchange performance by increasing the fluidity of fluids and by promoting turbulence of the fluids, including: heat exchange elements stacked by being laid one on top of another and individually formed by assembling upper and lower plates, with an internal flow channel defined in each of the heat exchange elements and an external flow channel defined between the heat exchange elements, the internal and external flow channels allowing internal and external fluids to pass therethrough, respectively, wherein the upper and lower plates are provided with respective wave patterns having ridges and valleys, each of the heat exchange elements has an inlet port and an outlet port, the upper and lower plates respectively have an upper flange and a lower flange which are assembled with each other through fitting, and first and second flat parts are formed around the upper and lower flanges.

Flexible finned heat exchanger

Abstract: A heat exchanger 36 for cooling an array of electric circuit chips 22 disposed on a common substrate 24 is formed as a flexible sheet 38 of thermally conducting material with upstanding fins 40 for transference of heat from the chips to a coolant flowing through the fins. The sheet may be provided with corrugations 44 set between sites of the chips for improved flexibility to accommodate individual orientations of the chips. The sheet is sufficiently large to cover an array of chips and is secured adheringly, as by use of a thermally conductive grease, to the chips. The sheet hermetically seals the chips from contamination by the coolant. The heat exchanger may be fabricated of copper with a nickel coating, wherein the copper provides the heat conduction and the nickel protects the copper from a corrosive coolant such as water. The finned sheet may be efficiently fabricated by processes analogous to those used to make printed circuits. In one embodiment of the heat exchanger, the fin thickness, the fin spacing and the sheet thickness are all approximately equal, a typical sheet thickness being approximately 0.05 mm.

Transport refrigeration system

Abstract: A transport refrigeration system (10) suitable for mounting on the front wall (14) of a narrow post highway trailer (15) in which the refrigeration system (10) intrudes into the trailer cargo space (17) only to the extent necessary to direct trailer air (89) into an evaporator coil (72). The evaporator coil (72) is completely serviceable external to the trailer (15), with its inlet surface (76) being substantially co-planar with the inside surface (80) of the front wall (14) of the trailer (15). An air delivery assembly (98) is manufactured as an integral unit and mounted in a main support frame (12) of the transport refrigeration system (10) without requiring further adjustment. Mounting of the air delivery assembly (98) on an intermediate wall (50) of support frame (12) completes a plenum chamber (119) for the evaporator coil (72), placing an axially narrow blower (106) into an air flow path in which the blower (106) draws trailer air (89) through the evaporator coil (72) and forces conditioned air (91) back into the trailer (15). Mounting of the air delivery assembly (98) also creates a condenser plenum (123) and places a fan (110) into an air flow path in which outside air (93) is directed upwardly through a condenser coil (90), and laterally through an engine radiator (94).

Process for producing power

Abstract: A process is disclosed for producing mechanical energy or electric power from chemical energy contained in a fuel, utilizing a combustion turbine. The compressed air which is used for combustion of the fuel to drive the turbine is humidified prior to combustion in a multistage countercurrent saturator to replace some or all of the thermal diluent air with water vapor. Humidification is effected with the water at a temperature below its boiling point at the operating pressure. The compressed air is cooled prior to humidification by passing in heat exchange relationship with the water used for humidification. Low level heat is rejected from the compressed air during intercooling and prior to humidification. This process provides a significant improvement in thermal efficiency, compared to combined cycle, steam injected cycle, intercooled regenerative cycle, and other air humidification based processes. Additionally, the entire steam cycle of a combined cycle process is eliminated, including the steam turbine generator, steam drums, surface condenser and cooling towers.

Deicing of a geared gas turbine engine

Abstract: A geared turbofan gas turbine engine has a fan rotor carrying a plurality of fan blades driven by a gas generator via a gear assembly. A fan casing which has an exterior surface is positioned coaxially with and encloses the fan rotor. A lubricant supply is provided to lubricate and cool the gear assembly and a heat exchanger is provided to cool the lubricant. An air scoop forms a first duct which supplies air to the heat exchanger to cool the lubricant. A second duct defined partially by the air scoop downstream of the heat exchanger and an annular chamber formed coaxially supplies air warmed in the fan casing by the heat exchanger to the exterior surface of the fan casing for deicing or anti-icing purposes. The air scoop and heat exchanger can be positioned on the fan casing, the gas generator casing or a pylon. A valve in the air scoop controls the flow of warmed air to the second duct.

Indirect evaporative cooling system

Abstract: An evaporative cooling system is disclosed which uses a heat pipe device comprising first and second heat exchangers to transfer heat from the space being cooled to an evaporative cooler. Evaporative cooling is produced by passing atmospheric air over wet pads and the first heat exchanger. Evaporation of water removes heat from the atmospheric air and from the first heat exchanger containing refrigerant vapor, causing condensation of a portion of the vapor. The condensate moves to the second heat exchanger which contains liquid refrigerant. Room air is passed through the second heat exchanger and gives up heat to vaporize the liquid refrigerant. Vaporized refrigerant moves to the first heat exchanger where it is condensed as previously described. The cooled atmospheric air is then used to cool the condenser of a vapor compression machine, the evaporator of which is located in the flow path of the room air downstream of the heat pipe, further cooling the room air to desired conditions. Evaporative coolers using heat pipe devices and arranged in multi-stage configurations to produce greater cooling effects are also disclosed.

Cooling system for electronic equipment

Abstract: A cooling system for maintaining the temperature within electronic equipment has a circulation system for pumping a cooling liquid, such as water, through the electronic equipment where it picks up heat generated by the electronic equipment. The cooling liquid is pumped through a plurality of heat exchangers using a refrigerant which is, in turn, pumped through a compressor-condensor combination, each heat exchanger having approximately the same cooling capacity. A central control selects the number of heat exchangers which are to operate at any given time, on a basis of the differential in the temperature of the water being pumped into and out of the electronic equipment. This maintains a desired and relatively wide range of temperatures. A heating element selectively and controllably heats the cooled water to bring the wide range of temperatures to a selected and fixed temperature.

Method and device for removing lint from a condensation-water separator are designed as a heat exchanger

Abstract: Method and device for removing lint from a condensation-water separator designed as a heat exchanger, in which the drying air is guided through air-guide chambers and the waste process air is guided in the same plane perpendicularly thereto between channels of the condensation-water separator which are formed by plates, and in which the condensate which occurs drips off from the plates, is collected in the collecting container and is pumped from their via a riser into a removable condensate-collecting container located higher in the laundry drier. Lint settles on the plate surfaces. According to the inventive method, this is flushed from the plates (4) by means of at least some of the condensate which occurs. For this purpose, the condensation-water separator designed as a heat exchanger (1) is provided with a laundry-lint flush-out device (10). The invention makes it possible for the operator, without much effort, to remove the lint from the condensation-water separator designed as a heat exchanger.

Passive safety system for a pressurized water nuclear reactor

Abstract: A passive safety system for a nuclear reactor is comprised of a first subsystem for circulating water solely by natural convection from a first branch to a second branch of a reactor coolant circuit with the circumvention of a steam generator for removing decay heat from the reactor coolant circuit at any pressure. There is also provided a second subsystem for introducing stored cold water solely by gravity into the reactor vessel for making up for lost water in the reactor coolant circuit at any pressure. The passive safety system further has a third subsystem for introducing stored cold water solely by gravity into the reactor vessel when the pressure with the reactor coolant circuit is reduced at least approximately to the same pressure as in the containment, for flooding the containment to a height above the first and second branches of the reactor coolant circuit.

Gas combination oven

Abstract: A gas-fired combination steam and dry oven has an oven cavity that is heated by heat exchange from one or more fire tubes and a boiler that is located outside the oven cavity and is heated by heat exchange from one or more other fire tubes. Both the oven and boiler fire tube heat exchangers employ natural draft gas burners. The combination oven can be operated as a forced-air convection oven, a forced-flow convection oven circulating superheated steam, or a steamer circulating saturated steam. Sensors in the oven supply information to a microprocessor that controls the gas burners to maintain an oven temperature within 5° F. or less. Sensors of the level of water in the boiler assure that the water level stays within predetermined limits. Tray stops keep foods and the trays containing them away from the walls of the oven to permit free circulation of air, saturated steam, or superheated steam. Sensors of water temperature in the boiler and of the circulating mixture of air and water vapor temperature in the oven chamber permit the control of relative humidity when the oven is used to proof dough or hold cooked food at a relatively low temperature. Control of the temperature of water in the boiler is aided by blowdown and replacement if the water temperature becomes too high.

Methods for comparing the performance of pure and mixed refrigerants in the vapour compression cycle

Abstract: Methods of comparing pure and mixed refrigerants are considered by computing the coefficient of performance and the heating capacity for an ideal vapour compression cycle for R22/R11 aand R22/R11 mixtures. For comparisons based only on one characteristic condensation temperature and one evaporation temperature, the results depend entirely on how the characteristic temperatures are defined. A method specifying the heat transfer fluid temperatures and a total heat exchanger area per unit capacity is thought to offer a comparison applicable to both pure and mixed refrigerants. Using this method, the effects of compressor superheat, heat exchanger approach temperatures, and the match of refrigerant and heat transfer fluid temperatures are discussed.

Temperature controlled picnic box

Abstract: A refrigerator/food warmer includes an insulated food compartment and lid. A thermoelectric heat exchanger and air circulator are mounted in the lid with both a heatsink of the thermoelectric heat exchanger and an air impeller of the air circulator above and below the lid, respectively. The air impeller above the lid draws air through the corresponding heat sink for improving the temperature differential between opposing sides of the thermoelectric heat exchanger, and the air impeller below the lid forces air of the insulated housing through the corresponding heat sink for conditioning the air hot or cold, as desired, and circulating the conditioned air throughout the insulated housing.

Effects of Some Types of Maldistribution on the Performance of Heat Exchangers

Abstract: The effects of several types and patterns of maldistribution in heat exchangers on the exchanger thermal performance are investigated. For turbulent flow most exchangers show only a small reduction in performance; however, for laminar flow the reduction can be large. It is shown that substantial errors in the apparent heat transfer coefficient occur for nonuniform flows.

Cryogenic ultrasonic scalpel

Abstract: Disclosure is made of a cryogenic ultrasonic scalpel comprising a housing, an ultrasonic source installed in said housing, a cutting means to which ultrasonic vibrations are supplied from the ultrasonic source via a transformer, a tubular heat exchanger featuring inlet and outlet pipes for the supply and removal of the refrigerant and providing the required low-temperature action on the tissue being dissected, and thermal insulation between said cutting means and said tubular heat exchanger.

Dehumidification: on the correlation of wet and dry transport processes in plate finned-tube heat exchangers

Abstract: The transverse velocity of the condensing phase during dehumidification is analogous to the transverse velocity at the wall when exercising boundary layer control by fluid extraction through a permeable wall. Wet and dry pressure drop and heat transfer rates are analyzed for correlation using boundary layer suction theory. Data are presented for flat-plate finned-tube heat exchangers during air heating and dehumidification operations and the data show a significant effect of transverse velocity correlated by the boundary layer suction formulation. The condensate film is considered isothermal in this analysis and the results indicate that an improved modeling of the condensate film is required. The authors find that the transverse velocity of the condensing phase has an important effect on transport phenomena during dehumidification and that the validity of the Chilton-Colburn heat and mass transfer analogy in describing dehumidification is supported by these results. It should be noted that the dry data form the beginning of a plate fin heat exchanger data base. The present data show the effect of tube diameter and, independently, fin density variation on the Colburn and friction factors with all other geometric parameters held invariant.

Desiccant air conditioning system

Abstract: A desiccant air conditioning system incorporates a desiccant material structure in the form of a heat exchanging desiccant bed. The heat exchanging desiccant bed is formed by granular desiccant material defining air passageways and liquid circulating channels for circulating heat transfer liquid in heat exchange relationship with the desiccant bed. The desiccant bed may include at least one stack of substantially parallel spaced-apart thermally conducting fins or plates with the granular desiccant material intimately bonded to the surfaces of the plates. The plates are provided by tube sheets or tube fins which include the tubes or channels for circulating heat transfer fluid. The method of air conditioning contemplates drawing building air to be conditioned through an adsorb air passageway; preconditioning the air by initially moisturizing or humidifying the air to substantially 100% relative humidity and adding heat to the moisture-laden air extracted from the air exiting from the desiccant bed. The preconditioned air enhances the ability to export or remove net latent heat and sensible heat energy from the system for better independent control of temperature and humidity. The preconditioned air passes through the heat exchanging desiccant bed for adsorption and condensation of excess water. At the same time cooling liquid circulating through the circulating channels of the desiccant bed exports and removes latent heat of condensation liberated by adsorption on the desiccant surfaces. A final step of evaporative chilling of the dried and cooled air brings the air condition parameters within the desired comfort zone range.

Dynamic Simulation of Shell-and-Tube Heat Exchangers

Abstract: The transient operation of a multipass shell-and-tube heat exchanger with baffles is described by a multicell dynamic model where every cell represents a specific part of the exchanger. The proposed modeling technique can be used in a digital computer for the dynamic simulation of almost any type of shell-and-tube heat exchanger. The model includes time-dependent inlet conditions for both the cold and the hot streams. Hence, a number of start-up cases can be simulated and, once the system reaches a stationary operating point, a disturbance can be introduced in the inlet temperatures or the flow rates. This particular feature makes the model very useful not only for design purposes but also for transient analysis and control system design.

Inverter-aided multisystem air conditioner with control functions of refrigerant distribution and superheating states

Abstract: A single outdoor unit has at least an inverter circuit, a compressor motor, a variable capacity compressor, and an outdoor heat exchanger. A plurality of indoor units each have at least an indoor heat exchanger and an air-conditioning load detector. A distribution unit couples the single outdoor unit to the plurality of indoor units in parallel by liquid-side refrigerant piping and gas-side refrigerant piping, to form a refrigerating cycle of a heat pump type. The liquid-side refrigerant piping includes a motor-operated flow regulating valve and pressure reducer, which are connected in series fashion. A pseudo-refrigerant superheating state detector detects a pseudo-refrigerant overheating state on the basis of the temperature of the refrigerant in the aggregated portion of gas-side refrigerant piping of the distribution unit. A first controller respectively controls the open factors of the motor-operated flow regulating valves. A second controller computes a total amount of the contents of the predetermined frequency data corresponding to a total air conditioning load of the indoor heat exchangers and controls the output frequency of the inverter circuit according to the total amount. A third controller incrementally controls the open factor of the motor-operated flow regulating valves to a value larger than the current value, on the basis of the detection result of the pseudo-refrigerant superheat state detector.

Prediction of cyclic heat pump performance with a fully distributed model and a comparison with experimental data

Abstract: A dynamic model of vapor compression heat pumps is presented. Due to the importance of thermal expansion and compressibility effects, a detailed mathematical treatment is given of the condenser, evaporator, and accumulator. A brief description is presented of the solution methodology employed in the complete heat pump model. Lumped-parameter models were developed for the expansion device, natural-gas-fueled IC engine, and compressor (open and hermetic). However, due to space limitations, these models will not be presented. Since inclusion of an appropriate void fraction model was found to be essential in determining the detailed refrigerant mass distribution, this topic is also discussed. Simulation results and experimental data are favorably compared for transient operation of a hermetic water-to-water heat pump and an air-to-air system with an open compressor. The spatial variations of temperature, enthalpy, mass flow rate, and density are predicted at each point in time for the two heat exchangers. The refrigerant pressures in the condenser and evaporator are determined such that the boundary conditions for the governing set of parabolic partial differential equations are satisfied. The summary provides a list of ongoing work in the area of heat pump simulation and applications.

Methods and apparatus for ocean thermal energy conversion using metal hydride heat exchangers

Abstract: Methods and apparatus for ocean thermal energy conversion using metal hydride heat exchangers to power a turbine by desorbing and absorbing hydrogen gas. Heat exchangers are alternatively floated to the ocean surface to warm the metal hydride bed or sunk to the bottom to cool the bed. The turbine powers an electric generator which produces electricity which may be utilized directly, stored in a superconducting magnet, used to desalinate water, or used to power the electrolysis of water in order to produce hydrogen for use as a fuel.

Multi-mode combustor

Abstract: An optimized thermal/catalytic combuster for the efficient oxidation of volatile organic compounds (VOC) in air. As an example, the invention is directly applicable to remedial action for clean-up of ground sites contaminated by spills or leaks of gasoline, organic paint solvents and the like, by a process known as air extraction. A thermal combuster and a catalytic oxidizer are interconnected by piping and control valves so that when one such element operates, the other is quiescent, depending on the concentration of combustible vapors in the extracted air. A dilution air valve, a heat exchanger, an electric heater, or a connection to a supplemental supply of clean-burning fuel, or all these devices, may be provided to ensure efficient operation. In an alternative embodiment, an internal combustion engine may be used in place of the thermal combuster. The engine can be used to supply power for other uses within the system or for external use. In a further alternative, a basic vapor contamination abatement system addressed specifically to extraction vapors from contaminated soils comprises a vacuum pump/compressor transmitting the vapors from the soil to a catalytic oxidizer, without use of a thermal combuster.

Heat exchanger for a fast cooldown cryostat

Abstract: A heat exchanger for a fast cooldown cryostat having high pressure and low pressure flow paths wherein a low pressure flow path is defined by a finely divided matrix which in turn defines a plurality of flow paths and said high pressure flow path is disposed in heat exchange relationshp to said matrix.

Thermoelectric heating and/or cooling system using liquid for heat exchange

Abstract: A water purification or filtration system supplies purified or filtered water into an unpressurized, heavily insulated reservoir. A thermoelectric module thermally coupled to the reservoir pumps heat into or out of the reservoir, heating or cooling the purified water. A flow director thermally coupled to the thermoelectric module "shapes" room temperature water, which may be brine wastewater produced by the purification system or tap water diverted from the main water line by an in-line flow restrictor into a thin sheet flowing through a thin passage in the flow directors. Pumped heat from the thermoelectric module thereby is efficiently absorbed by the thin sheets of water, which may be discharged into a drain. A sealed electric pump delivers purified or filtered cooled (or heated) water to a spigot in response to actuating of a control switch.

Low pressure drop condenser/heat pipe heat exchanger

Abstract: A thermal control system adapted for test in a 1G gravity environment and for operation as a microgravity environment includes a capillary pumped loop with a wicked evaporator which produces a coolant vapor head of about 1/2 PSI upon absorbing heat from a heat source. A heat pipe includes a cylindrical portion adapted for absorbing heat, and also includes a radiator panel which rejects absorbed heat. A heat exchanger coupled to receive coolant vapor from the wicked evaporator includes a manifold which directs the vapor to a plurality of parallel fluid channels helically wound about and thermally coupled with the heat absorbing portion of the heat pipe. A liquid manifold is coupled to the liquid side of the fluid channels for receiving cooled liquid, which is returned to the wicked evaporator. The helically disposed fluid channels are dimensioned so that the surface tension forces of the coolant liquid are at least large compared with gravitational forces, and so that the centrifugal forces due to the helical disposition of the fluid channel at least aid in making the flow regimes similar in both microgravity and 1-G testing conditions.

Cold plate refrigeration method and apparatus

Abstract: An improved cold storage refrigeration system and method is presented. A first heat exchanger located in a cold storage unit is connected by means of a series of vertical pipes to a second heat exchanger located below the first heat exchanger within a refrigerated space, forming an integrated tube assembly. To charge the cold storage unit, the tube assembly is operated as the evaporator of a conventional refrigeration circuit. During non-powered cooling, a portion of refrigerant is sealed within the tube assembly. The refrigerant vaporizes in the second heat exchanger and condenses in the first heat exchanger, thereby transferring heat from the refrigerated space to the cold storage unit. Defrosting of the second heat exchanger is accomplished by removing refrigerant from the second heat exchanger and circulating air above 0 degrees centrigrade around it.

Flexible hose heat exchanger construction

Abstract: A heat exchanger construction for melting snow, heating buildings or objects and transferring solar heat. The construction embodies a flexible, multilayered, reinforced composite hose (20) embedded in or affixed to a slab or other body. The composite construction combines the advantages of metal, extruded rubber and plastic piping to produce substantial durability, pressure rating, resistance to oxygen permeation, temperature tolerance, and corrosion resistance, while remaining extremely flexible and thus easy to install. Three embodiments are described and illustrated.

Expansion/evaporation cooling system for microelectronic devices

Abstract: Apparatus for cooling a semiconductor device by expansion cooling and/or evaporative cooling with a nontoxic gas includes a heat exchanger in thermal contact with the device to be cooled. A stream of expanding gas is released from a pressurized gas or liquid source through an expansion valve and is directed toward a heat exchange surface of the heat exchanger. The heat exchange surface includes fins which extend outwardly from the expansion valve and define grooves that direct the expanding gas over the heat exchange surface. The fins and grooves can be radial, spiral or branching for efficient thermal transfer. The grooves increase in cross-sectional area with radial distance from the expansion valve to accommodate the expanding gas volume. When a liquid is utilized, the liquid evaporates upon passing through the expansion valve, thereby providing both evaporative cooling and expansion cooling.

Combustion system and method with fog injection and heat exchange

Abstract: An ultrasonic fog generator can be used to advantage in injecting a fog into the input air of a combustion chamber, in order to improve efficiency and reduce the noxious emissions in the exhaust. In accordance with one form of the disclosure, a heat exchange is utilized to advantage in a turbine system in reheating compressed air that has been cooled as the air was fogged, the reheated air being input to the combustion chamber. In another form of the disclosure an adjustable heat exchange is used to controllably heat input air before the fogging thereof, the level of heat exchange depending on properties of the input air and the level of fogging to be implemented.

Catalytic air cleaner

Abstract: The invention is a catalytic air cleaner made from a double spiral formed by winding together two strips of metal. The strips are coated with a combustion catalyst. One spiral passage leads into the core of the spiral and the other passage leads out of the core. An electric resistance heater supplies heat at the core of the spiral. The outflowing air transfers this heat to the inflowing air, through the walls of the spiral. Because of this heat exchange, the difference between the temperature of the air at the core and the air entering the spiral can be many times the difference between the temperature of the air entering and leaving the spiral. Contaminants in the air are burned on the catalytic surface with a minimum input of heat. The invention also includes a method of designing a spiral having optimum characteristics.