Showing papers on "Heat exchanger published in 1984"

Low-Temperature Expansion Pulse Tubes

Abstract: Pulse tube refrigeration units using the Gifford-Longsworth cycle are remarkable among other types of low-temperature devices because of their simplicity and reliability. They are not widely used in cryogenics, however, because of their low efficiency and small refrigerating capacity, partly because of their low pulse frequency.

Finned heat exchanger

Abstract: A finned heat exchanger includes a plurality of elongated fins which are arranged at a predetermined interval in parallel with one another such that air flows between neighboring ones of the fins in a predetermined direction. A plurality of heat transfer tubes which contain refrigerant passing therethrough are orthogonally inserted through the fins so as to be arranged in a plurality of columns on the fins. When the finned heat exchanger is operated for condensation, the heat transfer tubes are provided in two paths in the vicinity of an inlet for the refrigerant and are provided in one path in the vicinity of an outlet for the refrigerant, such that the heat transfer tubes of the one path occupy about 5 to 30% of all the heat transfer tubes.

Cooling system for VLSI circuit chips

Abstract: A system for cooling integrated circuit chips and particularly those involving very large scale integrated circuits; the system provides for closely associating the heat-sink or heat exchange element with the integrated circuit chip by having the heat-sink, in the form of a "cooling chip", in intimate contact with the back surface of an integrated circuit chip (in a "flip chip" configuration, the front, or circuit-implemented, surface, makes contact with a ceramic carrier or module); the cooling chip is provided with a plurality of spaced parallel grooves which extend along the one side or surface opposite the surface that is in bearing contact with the integrated circuit chip, whereby liquid coolant flows through the grooves so as to remove heat from the integrated circuit chip; further included in the system is a specially configured bellows for conducting the liquid coolant from a source to the heat-sink, and for removing the liquid coolant; a coolant distribution means, in the form of at least one glass plate or manifold, is provided with spaced passageways interconnecting the respective incoming and outgoing coolant flow paths of the bellows with the heat-sink.

Heat transfer between gas fluidized beds of solid particles and the surfaces of immersed heat exchanger elements, part I

Abstract: After some general remarks about fluidization, and a section on the hydrodynamic behaviour of fluidized beds, the mechanisms of heat transfer between the surfaces of heat exchanger elements and gas—solid fluidized beds are discussed in detail. A theoretical model, presented some years ago, is slightly modified and further developed to improve its applicability within a wide range of variables. The model makes use of some of the basic concepts of molecular kinetic theory as applied to solid particles in a fluidized bed. A complete derivation as well as all the parameters required to apply the model equations are given.

Refrigerator for vehicle

Abstract: A refrigerator for vehicles has a cooling unit and a cool-keeping container adapted to be detachably connected to the cooling unit and contain goods to be cooled. The cooling unit includes a refrigerator evaporator connected to a refrigeration cycle of an automotive airconditioning refrigeration cycle on a vehicle and a coldness accumulating medium supported in heat exchange relationship with the evaporator. During evaporator operation, the coldness is accumulated in the coldness-accumulating medium and simultaneously transferred to the goods in the cool-keeping container. When the goods are cooled to a desired temperature, the cool-keeping container can be disconnected from the cooling unit and taken out of the vehicle with a heat insulating lid closing an opening formed in the container for the insertion and removal of the goods into and out of the container.

The plate heat exchanger: construction and design

Abstract: The gasketed plate heat exchanger is now commonly used in a wide range of applications. This paper details the construction of a plate heat exchanger (PHE) and its principles of operation. The capabilities are summarised in terms of operating pressures, temperatures and throughputs, followed by a discussion of its thermal and hydrodynamic characteristics. The paper highlights dimensionless characteristics for single phase heat exchange and discusses how these may be used in the analysis of a plate heat exchanger design. Finally qualitative and quantitative comparisons with shell and tube are given. The paper shows that within its capability range, the PHE is an excellent heat exchanger.

Heat pump closed loop drying

Abstract: A dryer includes a rotating drum (14) having an inlet (14A) and an outlet (14B). A blower (15) withdraws air from the outlet. A heat pump has an evaporator (17) and condenser (25) interconnected by a compressor (26) and an expansion valve (27). The outlet of the condenser is connected to the inlet of the rotating drum. The water collection tray (21) drains into a sump (23) having a sump pump (24). In a closed loop form the outlet of the rotating drum is coupled to inlet of the evaporator and is thermally coupled to a wet air heat exchanger (16).

Open cycle desiccant air-conditioning system and components thereof

Abstract: An open-cycle air-conditioning apparatus including a rotatable heat exchanger wheel, a rotatable moisture transfer wheel, evaporative elements, and heating means disposed between the heat exchanger wheel and the transfer wheel wherein both wheels are constructed of spaced alternate layers of material mounted on a hub with means for forming a plurality of axial passages in the area between the layers. The moisture transfer wheel has an absorbent material alternating with a rigid polymeric material and the heat exchanger has rigid material of a low thermal conductivity, such as a rigid polymer forming both layers. In each instance, axial passages exist between the layers. Both wheels have outer semi-rigid rims and a plurality of rigid spokes secured to and extending radially from the hub, through the material and the rim for structurally strengthening the wheels and terminating in a threaded end with a cooperating nut for truing the wheel through adjustment of the nuts. Baffles may be included between the two wheels on the air input side so as to prevent undesirable intermingling of air having different temperatures and humidities. A moisture impervious grid may be formed through the absorbent material to prevent migration of the desiccant material contained therein. Solar heat coils are used for the heating requirements.

Passive mold cooling and heating method

Abstract: A mold for molding articles of plastic or other like materials, having a plurality of vertically extending internal passages, is connected by inlet and return conduits into a closed loop that includes a heat exchanger partially filled with a liquid supply of a cooling fluid or a heating fluid. For cooling the heat exchanger is positioned with its liquid level above the top of the mold, the inlet conduit connects the lower part of the heat exchanger, below the liquid level, to the lower ends of the mold passages, and the return conduit connects the upper ends of the mold passages to the upper part of the heat exchanger; for heating these relationships are reversed. In operation the fluid changes its physical state at critical points in the mold passages, going from liquid to vapor for cooling and from vapor to liquid for heating; circulation in the closed loop is in response to the effect of gravity. Operation of the heat exchanger is controlled to maintain a controlled pressure in the closed loop.

Transient heat pump behaviour: a theoretical investigation

Abstract: A detailed mathematical model of vapour compression heat pumps is described. Model equations of the various heat pump components are given. The component models include the condenser, evaporator, accumulator, expansion device, and compressor. A brief discussion of the modelling techniques is presented, as is the solution methodology. Preliminary simulation results are also illustrated. The model developed predicts the spatial values of temperature and enthalpy as functions of time for the two heat exchangers. The temperatures and enthalpies in the accumulator, compressor and expansion device are modelled in lumped-parameter fashion. Pressure responses are determined by using continuity satisfying models for both the condenser and evaporator. The summary provides a list of future work anticipated in the area of dynamic heat pump modelling.

Heat exchanger with fin

Abstract: PURPOSE: To prevent the occurrence of choking due to frosting an lowering of a draft amount, to improve heat exchange capacity, and to enable increase of a heating operation continuous time by a method wherein a heat transfer pipe is arranged downstream of an air flow from the central part of a fin, a waveform cut rise is formed in the portion, on the upper stream side of an air flow, of the fin, and a slitform cut rise is formed in the portion, on the downstream side of the air flow, of the fin. CONSTITUTION: Fins 11 are arranged in parallel at intervals of a specified distance to form a fin group 12, and an air flow passes therebetween. A heat transfer pipe 13 inserted through the fin group 12 at right angles is provided down an air flow B from the central part of the fin 11. A waveform cut rise 14 is formed in the portion, on the upper stream side of the air flow B, of the fin 11 and a slitform cut rise 15 in the portion, on the downstream side of the air flow B, of the fin. Thus, when the temperature of the air flow B is reduced and a vaporizing temperature is reduced to 0°C or lower, the surface temperature, on the upper stream side of the air flow B, of the fin 11 is increased, frosting is difficult to make. Since heat transfer is promoted on the downstream side of the air flow B, frosting is easy to make, and a frost layer is formed synthetically relatively uniformly. A draft passage is ensured, and further since the waveform cut rise 14 and the slitform cut rise 15 are formed, thermal conductivity is improved and heat exchange capacity is also enhanced by means of a turbulence promoting effect and a boundary layer frontal line effect. COPYRIGHT: (C)1990,JPO&Japio

Energy efficient air conditioning system utilizing a variable speed compressor and integrally-related expansion valves

Abstract: Disclosed is an improved air conditioning system of the type having a refrigerant which sequentially flows through compressor means, condenser means in heat exchange relationship with outdoor air, expansion means, and evaporator means for the direct or indirect cooling of air in a confined space for maintaining the confined air space at a desired set point of temperature and/or humidity. The improvement for maintaining said set point of temperature and/or humidity of the confined space at variable heat loads therein and at variable outdoor air temperature comprises variable speed compressor means responsive to varying outdoor air temperature for attenuating refrigerant mass flow corresponding to lower outdoor air temperature; and expansion means responsive to attenuated refrigerant mass flow for maintaining adequate refrigerant mass flow to the evaporator means for maintaining constant the desired set point of temperature and/or humidity of the confined space at varying outdoor air temperature.

Heat exchanger method and apparatus

Abstract: Exhaust gas treatment method and apparatus extract heat from an exhaust gas by operating in a water-condensing mode which allows more heat to be recovered, removes particulate matter and condensed acid from the exhaust gas, and washes heat exchange surfaces to keep them clean and wet to improve heat transfer. Systems for heating water, air, and both water and air are disclosed. Methods of constructing and assembling improved heat exchangers are disclosed.

Operating characteristics of a metal hydride heat pump for generating cooled air

Abstract: A metal hydride heat pump was constructed and the dependence of its operating characteristics on such variables as the pressure-temperature-concentration and kinetic properties of paired hydrides, the heat transfer performance of the heat exchangers, the amount of hydrogen gas with which the system was charged, the cycle time, the mass flow rate of the air supply and the operating temperature was investigated. The optimum operation conditions and parameters were evaluated and will be used as guidelines for future heat pump designs.

Chemically assisted mechanical refrigeration process

Abstract: There is provided a chemically assisted mechanical refrigeration process including the steps of: mechanically compressing a refrigerant stream which includes vaporized refrigerant; contacting the refrigerant with a solvent in a mixer (11) at a pressure sufficient to promote substantial dissolving of the refrigerant in the solvent in the mixer (11) to form a refrigerant-solvent solution while concurrently placing the solution in heat exchange relation with a working medium to transfer energy to the working medium, said refrigerant-solvent solution exhibiting a negative deviation from Raoult's Law; reducing the pressure over the refrigerant-solvent solution in an evaporator (10) to allow the refrigerant to vaporize and substantially separate from the solvent while concurrently placing the evolving refrigerant-solvent solution in heat exchange relation with a working medium to remove energy from the working medium to thereby form a refrigerant stream and a solvent stream; and passing the solvent and refrigerant stream from the evaporator.

Energy-efficient evaporation process with means for vapor recovery

Abstract: In a process for the recovery and reuse of heat contained in the wet exhaust gases emanating from a solids dryer or liquor concentrator (1), particularly one in which drying or concentration is facilitated by purging the vapor with some noncondensable gas such as as air or nitrogen, water or solvent vapor in the moist exhaust mixture is separated from the noncondensable gas or gases by preferentially passing the vapor through a semipermeable membrane (2). The water or solvent vapor is then compressed and subsequently condensed in a heat exchanger (4), permitting recovery of its latent heat of vaporization for reuse in the evaporation process. In a drying process, this recovered energy is conveniently used to reheat the dry gases that exit from the membrane separator (2), permitting the hot, dry gases to be recirculated through the dryer (1). Alternatively, an indirect heat exchanger may be used to transfer this heat to the material being dried. In an evaporative process forthe concentration of a liquor, the recovered energy may be used either to preheat the dry purge gases or to heat the dilute liquor being concentrated.

Transient Response of the Counterflow Heat Exchanger

Abstract: Calcul de la variation de la temperature de sortie d'un fluide d'un echangeur de chaleur a contrecourant due a un saut de temperature d'entree de l'un ou l'autre des fluides

Method for recyclying energy in counterflow heat exchange and distillation

Abstract: This document describes an improved method and apparatus for recycling energy in counterflow heat exchange and distillation. The basis of the invention is transferring heat with thin sheets of material having extensive surface area relative to the flow rate through the system. A distillation apparatus (11 and 12), a counterflow heat exchanger (11), a clothes dryer (FIG. 9), a power generator (FIG. 12), and other embodiments of the invention are described.

Drilled well series and paralleled heat exchange systems

Abstract: A system for exchanging thermal energy between a fluid medium and the earth is provided employing a number of boreholes drilled vertically in the earth spaced apart by adjacent intervals. An upflow conduit and a downflow conduit are placed in parallel relationship within the boreholes and connected at their lower ends. At the top of each borehole there is a header providing means to conduct fluid through the conduits in each borehole in a parallel or series arrangement. In each of the headers there is a partition dividing the flow of fluid passing downwardly into the borehole from the flow of fluid passing upwardly out of the borehole with a vent in the partition so that air which might otherwise be trapped in the verical conduits can by vented to prevent airlock of the system.

High efficiency air-conditioner/dehumidifier

Abstract: The system in the present invention includes HVAC unit, such as an air-conditioner, having an evaporator coil, and a heat exchanger for drawing heat from air entering the inlet side of the air-conditioner evaporator and supplying heat to air at the outlet side of the air-conditioner evaporator. The heat exchanger is a phase change heat pipe-type heat exchanger, having a evaporator before the air-conditioning evaporator and a condenser after the air-conditioner evaporator.

Beverage dispensing apparatus

Abstract: The invention relates to beverage dispensing apparatus of the kind comprising a tank, heater for heating a liquid contained therein, and container for storing concentrated beverage and dispensing it to a mixing chamber An object of the present invention is to provide such dispensing apparatus, in which provision is made for dispensing beverages with an alternative ingredient to water, or an additional liquid ingredient, such as milk The invention is characterized in that a pump is provided for feeding a liquid ingredient (eg milk or other dairy product), through the water tank for indirect heat exchange therewith, in that a temperature controlled mechanism is provided for controlling the outlet temperature of the liquid ingredient from the tank, and in that the liquid ingredient is fed in controlled, pre-determined quantities as required, to the mixing chamber Normally, the liquid within the tank would be water and, where this water is to be used for beverage making as well as the liquid ingredient, the water tank would be provided with an outlet for feeding predetermined quantities of hot water via controlled valve system to the mixing chamber

Heat exchanger with fins

Abstract: PURPOSE: To improve a dropping of water drpplets condensed at fins and restrict an increasing of aeration resistance of air flow and a decreasing of a thermal transmitting efficiency by a method wherein some space holding pieces having a wider width of an extreme end than that of a root part are positioned at a rear part of a thermal transmitting pipe in respect to a direction of air flow and further applied as projections in parallel with a direction of their gravities. CONSTITUTION: Some space holding pieces 12 having wider cut and raised end edges than widths of roots and further having widths of the cut and raised end edges smaller than a width of a thermal transmitting pipe at several fins 11 arranged at a specified spacing are positioned at a rear part of the thermal transmitting pipe in respect to an air flow and formed as projections in parallel with a direction of their weight. The heat exchanger having fins is used as an evaporator and in case that water droplets are condensed at an outer surface of the evaporator, the space holding pieces 12 are in parallel with their weighing directions, so that no water droplets are accumulated and when the condensed water droplets are dropped below the heat exchanger by their own weights, the spacing holding pieces 12 do not make any troubles to improve a dropping of the water droplets, and increasing of the aeration resistance of the air flow and a reduction of a thermal transmitting efficiency of the air flow are restricted. COPYRIGHT: (C)1991,JPO&Japio

Heat exchanger with temperature responsive bypass

Abstract: A heat exchanger for exchanging heat between engine lubricating oil and engine coolant comprises a heat exchange element made up of a plurality of stacked and spaced plate type heat exchange units. The heat exchange units are provided with successive flow openings through which the oil introduced from an inlet opening flows. A bypass valve is provided to control the flow of the oil passing through a bypass opening which is in communication with the flow openings of the heat exchange units. The bypass valve is of the oil temperature responsive type and adapted to open the bypass opening at oil temperatures below a predetermined level, thereby bypassing much of the oil in the heat exchange units when oil temperature is so low that cooling of the oil is unnecessary.

Apparatus for preheating combustion air, accompanied by simultaneous reduction of NOx contained in the flue gases

Abstract: An apparatus in the form of an air preheater for preheating air for combustion for a combustion process by acting upon the air with hot, NOx -containing flue gases from the same or an independent combustion process. At the same time, the NOx contained in the flue gases is reduced. A regenerative or recuperative type air preheater is used, with those surfaces of the heat exchange elements which are exposed to the flue gas being provided with a coating which acts as a catalyst for the NOx reduction. The heat exchange elements are coated only in a region which has a flue gas temperature greater than the condensation temperature of the reaction products of the materials contained in the flue gas and of the added reducing agent. The catalyst coating is provided on individual heat exchange elements which are successively disposed in the direction of flow of the flue gas in such a way that the respective coatings are optimally adapted to the reaction conditions for the flue gas temperature which exists in that region.

Multi-room type air conditioner

Abstract: A multi-room type air-conditioner includes an outdoor unit and a plurality of indoor units connected thereto and is capable of providing cooling and hearing by change-over of a 4-way valve. A plurality of motorized valves are provided on each liquid line of the outdoor unit, respectively in order to control superheat of low pressure gaseous refrigerant at the use-side heat exchanger outlet of each indoor unit in cooling and also to control sub-cool of high pressure liquid refrigerant at the heat exchanger outlet in heating. The motorized valve is completely closed in cooling mode for the non-operating indoor unit and the motorized valve for the non-operating indoor unit is controlled in the heating mode to have a small opening so that no liquid refrigerant accumulation takes place in the non-operating indoor unit.

Temperature control system for internal combustion engine

Abstract: @ When additional heat exchangers, such as oil coolers (11) and turbocharged air coolers (12), are mounted in front of or within the normal coolant heat exchanger or radiator (10) of an internal combustion engine, a variable speed fan drive (14) may be employed to blow air through all of the heat exchangers to cool the various fluids flowing through those heat exchangers. Since the different fluids usually have different desired operating temperature ranges for optimum engine performance, controlling the variable speed fan drive (14) only in response to the temperature ofthe engine coolant can result in overheating of at least one of the other fluids. This is avoided by temperature sensing (16,31,37) the different fluids and effectively determining which one of them has the highest relative temperature in its operating range. The fan drive is then controlled in response to the sensed temperature of that particular fluid. In this way, all of the fluids will be maintained within their desired operating temperature ranges. If the condenser (13) of an air conditioning system is also positioned in front of the engine coolant radiator (10), the compressor discharge pressure in the system may be monitored (66) and if it exceeds a preset maximum allowable level the fan is automatically driven atfull speed to maximize the air pulled in through the condenser, and of course through all of the other heat exchangers, to quickly decrease the refrigerant temperature and thus the discharge pressure.

Method of controlling refrigeration cycle

Abstract: In a method of controlling a refrigeration cycle constructed by connecting a compressor, an outdoor-side heat exchanger, an expansion valve, and an indoor-side heat exchanger, the temperature of a coolant ejected from the compressor is detected by a sensor, and the opening rate of the valve is adjusted in accordance with the detected temperature. When the detected temperature exceeds a prescribed upper limit, that opening rate of the valve which is indicated on that occasion is stored in a memory, and then the opening rate of the valve is increased to reduce the temperature of the ejected coolant to a lower level than a prescribed lower limit. After the temperature decreases from the lower limit, the opening rate of the valve is adjusted to a larger level than that level which is previously stored in a memory by a prescribed extent, thereby keeping the temperature of the ejected coolant between the upper and lower limits.

Continuous flow laundry system and method

Abstract: A continuous flow laundry system and method incor­porates a fluid flow control, temperature control, and heat recovery systems. Steam 38 is injected into the system to derive appropriate temperatures for washing laundry; rinse water 36 is provided at a predetermined elevated temp­erature by passing fresh water 95 through a heat exchanger 80 to derive heat from designated outflows of the system. As soiled laundry enters the system to flow counter to the washing fluid flow, it is subjected to a flushing section provided with flush water 75 at a reduced elevated temperature; the laundry is then passed through a washing section 13-18 where it is subjected to water at an elevated temperature for the washing cycle. The washed laundry is passed to a rinse section (19-22) and subsequently to an extract­or section 31 for removal of excess water therefrom. Out­flow rinse water 50 is combined with water from the extract­or 35 and supplied to the heat exchanger 80; a portion of this combined outflow 105 is shunted around the heat exchanger to be mixed with the outflow passing through the heat ex­changer 85 to control the temperature of the water supplied to the flush section 11-12. Outflow (72,62) from the wash and flush sections is combined and supplied to the heat exchanger (80) for extraction of heat therefrom to elevate the temper­ature of the fresh water 95 in the heat exchanger to be supplied to the rinse section. (19-22)