King Fahd University of Petroleum and Minerals

Muhammad Umar Siddiqui

Syed A M Said

Syed Ahmed Mohammad Said

Mohamed A Habib

Rached Ben Mansour

Maged A I El-Shaarawi

An intermittent operation based continuous absorption system (IOBCAS) which supports cooling effect during the daytime without the use of a solution pump is provided. The IOBCAS may utilize an isochoric process for pressurization of the system and the system may include a plurality of generator-absorber units that intermittently operate in succession to provide a continuous refrigeration cooling effect during the daytime. The system of the present disclosure enables the plurality of generator-absorber units to switch between a generation, absorption, and heat recovery mode of operation to provide cooling effect during the daytime which a higher coefficient of performance compared with conventional intermittent system.

Continuous adsorption cooling system with air-cooled heat rejection unit

The heat exchanger is adapted for cooling a coolant (e.g., water), used to cool a device or an area (e.g., building interior), such as during periods of peak energy cost and usage, to save energy and energy costs. The heat exchanger includes a coolant storage tank with one or more refrigerant circulators in contact with the floor of the tank. The circulators use a refrigerant having a freezing temperature colder than the coolant, with coolant on the floor of the tank forming a layer of ice thereon. A rotary scraper extends up through the tank floor from each circulator, with the scrapers operating to remove the thin layer of ice from the floor as the ice forms. The resulting ice chips are relatively small and thin, thus having a relatively large surface area for their volume in order to maximize melting and rapid cooling of the coolant.

Coolant heat exchanger having a scraper for each heat exchange interface surface

Solar powered intermittent operation based continuous absorption system

The intermittent absorption refrigeration system includes a primary circuit having a generator/absorber, a dephlegmator, a condenser, an evaporator, and solar collectors to provide heat to the generator. The system also includes an ejector-based secondary circuit having a generator/absorber, an ejector, a condenser, a refrigerant storage unit, and solar collectors. Both circuits are aqua-ammonia systems, using ammonia as the refrigerant and water as the absorber liquid. The ejector permits evaporation during the daytime and storage of liquid ammonia refrigerant that is used for cooling in the heat exchanger of the primary circuit condenser and in the primary circuit absorber, thus permitting the primary circuit evaporator to operate at lower temperatures for low temperature freezing applications in the daytime, even at high ambient temperature.

Intermittent absorption refrigeration system

The intermittent absorption refrigeration system with an ejector includes a generator/absorber unit, a solar collector unit, a dephlegmator, a condenser unit, a first evaporator, and valves to control the flow of aqua-ammonia coolant through the system, as in a conventional intermittent absorption refrigeration system. However, the present system also includes an ejector disposed between the dephlegmator and the condenser, and also a second evaporator disposed in a feedback loop between the first evaporator and the ejector, together with appropriate valves to control coolant flow through the feedback loop. The utilization of the ejector and the feedback loop in the intermittent system allows the intermittent system to produce a cooling effect during the daytime, as well as during the nighttime, which increases the coefficient of performance of the intermittent system.

Intermittent absorption refrigeration system with an ejector

The heat exchanger flow balancing system serves to substantially equalize fluid flow through essentially identical diameter heat exchanger tubes in a heat exchanger having a single inlet plenum, a single outlet plenum, and a series of equal diameter heat exchanger tubes extending therebetween. In one embodiment, a series of different diameter orifices are provided at the inlet end of each of the tubes, with those tubes farther from the single larger diameter inlet pipe to the plenum generally having smaller orifices. In another embodiment, each of the tubes is provided with a conical nozzle at its inlet end, with those tubes farther from the single inlet pipe to the plenum generally having smaller diameter nozzles. The effect is to substantially equalize fluid flow through all of the heat exchanger tubes, thus increasing the efficiency of the heat exchanger.

Heat exchanger flow balancing system

An economizer for a solar powered intermittent absorption refrigeration system improves the coefficient of performance of the refrigeration system. The economizer recovers waste energy rejected by an absorber during an absorption process, stores the waste energy, and supplies the waste energy to a generator during a generation process, thereby reducing the amount of energy input needed to operate the system.

Economizer for an intermittent absorption refrigeration system

The intermittent absorption system with a liquid-liquid heat exchanger includes two generator/absorber units that operate out-of-phase, a solar collector unit, a dephlegmator, a condenser unit, an evaporator, and valves to control the flow of aqua-ammonia coolant through the system. The system operates on a two-day cycle. On the first day, during the daytime, the first generator/absorber unit generates liquid ammonia, while on the second day of the cycle, the roles are reversed, the second generator/absorber unit generating liquid ammonia. At the start of each day, one generator/absorber unit is partially pressurized and the other partially depressurized by liquid-liquid heat exchange between their heat exchangers, followed by disconnecting the heat exchangers from each other and connecting the generator to the solar collector to complete pressurization. The liquid-liquid heat exchange between the generator/absorber units reduces the heat required from the solar collector to generate liquid ammonia refrigerant, improving the coefficient of performance.

Intermittent absorption system with a liquid-liquid heat exchanger

A solar powered intermittent absorption refrigeration system utilizes helical coil heat exchangers for generation, absorption, dephlegmation, condensation and heat recovery. The thermo-siphon effect is used to supply and reject heat from the system, to recover and utilize heat from a waste energy unit, to reject heat of absorption, and to pressurize and depressurize the system. The system produces ice blocks during the nighttime without any requirement of electrical energy for the operation of the system.

Intermittent absorption refrigeration system equipped with a waste energy storage unit

The hybrid aqua-ammonia and lithium bromide-water absorption chiller is an aqua-ammonia absorption refrigeration system integrated with a lithium bromide-water absorption refrigeration system. By integrating a solar-powered lithium bromide-water absorption refrigeration system into the aqua-ammonia absorption refrigeration system, evaporator temperatures below the freezing point of water may be generated at lower operating pressures and lower generator temperatures than in conventional aqua-ammonia absorption refrigeration systems.

Growing community of inventors

Dhahran, Saudi Arabia

Muhammad Umar Siddiqui