Showing papers on "Absorption refrigerator published in 1993"

Cooling capacity optimization of a waste heat absorption refrigeration cycle

Abstract: A finite-time endoreversible heat-driven absorption refrigerator is modeled thermodynamically in this paper. The refrigerator uses low-temperature waste heat directly to provide a cooling effect. The maximum cooling capacity delivered by the absorption system is analyzed.

Experiments on an absorption refrigeration system powered by a solar pond

Abstract: A heat source at temperatures not higher than 80°C was used to simulate the heat input to an absorption refrigerator from a solar pond. A laboratory model of an absorption refrigerator, using an ammonia-water solution at 52% concentration by weight, was operated intermittently using this heat source. Generation temperatures as high as 73°C and evaporation temperatures as low as −2°C were obtained. Tap water was used to remove the heat generated from the condensation of the ammonia vapour and the absorption of the refrigerant in the water. The temperature of the tap water was near the ambient laboratory temperature of 28°C. The COP for this unit working under such conditions was in the range 0.24–0.28.

Thermoacoustic life sciences refrigerator

Abstract: This thermoacoustic refrigerator is being built to preserve biological samples (blood, urine, etc.) during Space Shuttle operations. It employs two high‐power electrodynamic drivers capable of generating 60 W of acoustic power each, two ‘‘stacks,’’ and four internal heat exchangers in order to produce 700 BTU/h (205 W) of cooling in the refrigerator mode at 4 °C and 400 BTU/h (117 W) of cooling in the freezer mode at −22 °C. The working fluid is a 2‐MPa mixture of He and Xe gas. Both hot and cold heat exchangers use circulating fluids to remove heat from the insulated sample enclosure and exhaust enthalpy from the engine. This talk will describe the acoustical design and electronic control systems that permit long‐term autonomous operation while on orbit. Except for the fact that the entire systems operates from a 28‐Vdc power supply, it is not unlike a typical small household refrigerator. [Work supported by NASA—Life Sciences Division and managed by General Electric Government Systems.]

Refrigerator using external ambient cool air

Abstract: The refrigerator for use in a heated dwelling, allows the interior of the cabinet to be brought to a lower temp. by heat exchange with relatively cold external ambient air, to assist the cooling circuit. The ambient air is pref. supplied to the refrigerator heat exchanger via a feed pump controlled by a thermostat, which only switches in the pump when the ambient air is sufficiently cold, to provide an effective cooling. ADVANTAGE - Provides effective cooling with min. energy consumption.

Air-conditioning unit for vehicle - has heat-exchanger mounted on exhaust manifold and connected to refrigerator unit with cooling air and secondary heat exchanger

Abstract: An air-conditioning unit for a car functions on the absorption principle to remove as much as possible of the waste heat from the engine. There is a heat exchanger (2) connected in series with a refrigerator unit (1), the heat exchanger being mounted on the exhaust manifold (3). It is connected via two pipes to the refrigerator unit. The heat transporting medium between the two is either air or oil. The refrigerator unit (1) comprises a condenser, a boiler and an evaporator, all fully enclosed. There is a cooling fan to pass air through the unit. A second heat exchanger is connected via a circulating pump using a water/antifreeze mixture or oil as transport medium. A secondary energy source for heat supply to the refrigeration unit is provided and is supplied with electricity derived from solar cells mounted on the vehicle. ADVANTAGE- Simple assembly using available energy from the car as efficiently as possible.

Configuration and reliability of an air-conditioning system for telecommunications systems that uses the heat dissipated from fuel cells

Abstract: NTT Power and Building Facilities Inc., is now developing an air conditioning system for telecommunications use that uses the heat dissipated from phosphoric acid fuel cells. The authors have investigated the reliability of the air conditioning system and have found that the reliability of such a system can be improved if either multiple absorption refrigerators are used, or if a back-up heat supply facility (burner) is installed in an absorption refrigerator. They have also found that both an exhaust heat-driven air conditioning system and an electrically driven distributed air conditioning system must be combined to meet the reliability level required of air conditioning for telecommunications systems. In such a configuration, the number of air conditioners in the electrically driven distributed air conditioning system can be reduced by 30%. >

Absorption refrigerator and water cooler-heater with both low temperature regenerator and exhaust heat recovering low temperature regenerator

Abstract: PURPOSE: To improve a coefficient of performance and to save fuel to be consumed by a high temperature regenerator in an absorption refrigerator and water cooler-heater. CONSTITUTION: An exhaust heat recovering low temperature regenerator 62 is provided between a low temperature regenerator 2 and a high temperature regenerator 64. The regenerator 64 is connected to the regenerator 62 through a combustion exhaust gas duct 66 to introduce combustion exhaust gas used to concentrate absorption liquid to the regenerator 62, thereby concentrating part of dilute solution fed from an absorber 7. Refrigerant vapor generated in the regenerator 64 is introduced into the regenerator 2 to concentrate residue of the dilute solution fed from the absorber 7. COPYRIGHT: (C)1994,JPO&Japio

Mixed compression/absorption refrigeration device

Abstract: The present invention relates in general to methods and devices intended for refrigeration or heating of fluids, and more particularly to a novel device of so-called mixed compression/absorption refrigeration design, the absorption circuit of which is hermetic. In the current state of the art, refrigeration methods and devices often give up a large amount of heat energy due to the desuperheating and condensation of a coolant fluid, into the atmosphere, which energy is lost and very costly. The method according to the invention, called mixed refrigeration by compression/absorption, with or without hermetic absorption, makes it possible to recover and employ the heat energy from a thermal load to be refrigerated and to use it for refrigerating this same thermal load, or a different thermal load.

Chilled water temperature controller for absorption refrigerator

Abstract: PURPOSE:To obtain chilled water of a constant temperature by controlling an opening of a flow control valve of coolant as an outlet temperature rises and a pressure in an evaporator falls, and so controlling quantity of heat of a high pressure generator as to hold a refrigerant liquid level of a storage unit constant. CONSTITUTION:A regulator 59 so controls an opening of a flow control valve 58 in response to an output of a flowmeter 60 as to become an opening of an output from first control means 56. As a pressure in an evaporator 2 falls, a flow rate of coolant is varied to that corresponding to an output temperature. Cooling capacity of a heat transfer tube 10 in an absorber 9 is increased, and the temperature of the tube 10 is lowered. Pressures in the absorber 9, and the evaporator 2 are lowered, an evaporating amount of refrigerant to be scattered to a heat transfer tube 3 from nozzles 8, 38 is increased, an output temperature of chilled water flowing through the tube 3 is lowered to become a target temperature. When a liquid level of a storage unit 34 exceeds a level corresponding to a target load, an opening of a vapor flow control valve 44 is reduced to decrease quantity of heat to a high pressure generator 19 thereby to weaken heat attraction force from the tube 3 due to evaporation of the evaporator 2. Thus, the liquid level is always held constant.

Method and device for cooling fluid, particularly air by two separated absorption cooling system

Abstract: PURPOSE: To reduce power consumption by cooling air by two separated absorption cooling systems. CONSTITUTION: Liquid in absorbers 2 and 2 is cooled by heat exchangers 5A and 20 for cooling. The heat exchanger 20 for cooling for a rare absorption liquid that exists in the absorber 2A forms one portion of a cooling circuit including a radiator 21, and the radiator 21 transfers heat to the air in the external environment. In the heat exchanger 5 of a first device, cold water from an evaporator 1 absorbs heat, so that cooled air passing through the heat exchanger 5 cools a vehicle and a building. On the other hand, cold water from the evaporator 1A flows through the heat exchanger 5A of a second device, and the water absorbs heat, so that the heat exchanger 5A cools the rare absorption liquid in the absorber 2 of the first device.

Absorption type hot and chilled water generator

Abstract: PURPOSE:To stabilize the circulation of absorption liquid by branching a refrigerant vapor pipeline communicated with a high temperature regenerator, opening one branched line to a condenser by way of a low temperature regenerator and a valve and the other branched line to the condenser by way of a valve alone and communicating the high temperature regenerator inlet side of an intermediate liquid pipeline with a pump inlet side of an enriched liquid pipeline by way of a valve-equipped absorption liquid pipeline in terms of a double effect absorption refrigerator. CONSTITUTION:When solenoid valves V1 and V3 are opened while solenoid valves V2 and V4 are closed, cooling operation will be carried out in standard double effect mode. On the other hand, when the solenoid valves V1 and V3 are closed while the solenoid valves 2 and 4 are opened, a pump 5 will feed an intermediate liquid discharged from a high temperature regenerator 1 to an absorber 5 by way of an intermediate liquid pipeline 14, the solenoid valve 4 and a low temperature heat exchanger 7, which eliminates resistance troubles of the heat exchanger. The refrigerant vapor generated in the high temperature regenerator 1 is directly fed into a vaporizer 3 by way of the valve 2 to heat a water pipeline 31. Since the absorption liquid of the absorber 5 is heated when the refrigerant vapor is absorbed, this construction enhances thermal efficiency and functions as a single effect heat pump.

Food Preservation Processes

Abstract: The absorption refrigeration cycle often referred to as the Platen-Munters System employs the evaporation of a volatile refrigerant in order to produce a cold environment, and an adsorbent (either liquid or solid) to produce continuous movement of the refrigerant. In the simplest form, the cycle is operated by heating a solution of ammonia in water, thereby liberating ammonia gas which is condensed to give liquid ammonia. The liquid ammonia passes through the refrigerated compartment where the food is stored, and by evaporation liberates latent heat, thereby producing the cold environment. The process is maintained by absorbing the evaporated ammonia in water and repeating the cycle. The temperature may be varied by including hydrogen gas in the system; the greater the amount of hydrogen, the lower the temperature which may be achieved. To produce a temperature of − 18°C (0°F) the ammonia must boil at 0.1 MPa, which requires a pressure of hydrogen 2.65 MPa. The total pressure in the system is 2.75 MPa, and consequently a robust contruction is required.