Integration of LiBr-H2O Vapor Absorption Refrigeration Cycle And Power Cycle

Energy-conservation and environmental protection are keys to sustainable development of domestic economy. The solar-assisted cascade refrigeration cycle system is developed. The system consists of electricity-driven vapor compression refrigeration system and solar-driven vapor absorption refrigeration system. The vapor compression refrigeration system is connected in series with vapor absorption refrigeration system. Refrigerant and solution reservoirs are designed to store potential to keep the system operating continuously without sunlight. The results indicate that the system obtains pretty higher COP as compared with the conventional vapor compression refrigeration system. COP of the new-type vapor compression refrigeration system increases as sunlight becomes intense.

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Second Law Analysis of a Novel Combined Cooling and Power Cycle With Water Harvesting

Volume 5: Turbo Expo 2005 ◽

10.1115/gt2005-68628 ◽

2005 ◽

Cited By ~ 3

Author(s):

J. R. Khan ◽

W. E. Lear ◽

S. A. Sherif ◽

John F. Crittenden

Keyword(s):

High Pressure ◽

Absorption Refrigeration ◽

Refrigeration System ◽

Ambient Conditions ◽

Power Cycle ◽

High Pressure Compressor ◽

Vapor Absorption ◽

Absorption Refrigeration System ◽

Vapor Absorption Refrigeration ◽

Pressure Compressor

The first and second laws of thermodynamics were used to analyze a novel cooling and power cycle that combines a semi-closed cycle called the High Pressure Regenerative Turbine Engine (HPRTE) with a vapor absorption refrigeration system (VARS). Waste heat from the recirculated combustion gas of the HPRTE is used to power the absorption refrigeration unit, which cools the high-pressure compressor inlet of the HPRTE to below ambient conditions and also produces excess refrigeration in an amount that depends on ambient conditions. The cycle is modeled using steady-state thermodynamics, with state-of-the-art polytropic efficiencies and pressure drops for the turbo-machinery and heat exchangers, and accurate correlations for the properties of the NH3-water mixture and the combustion products. Exergy analyses were performed for all the components of the cycle to examine the losses and identify critical plant devices considering different operating conditions. Water produced as a product of combustion is intentionally condensed in the evaporator of the VARS, which is designed to provide sufficient cooling for: the inlet air to the high pressure compressor, water extraction and for an external load. The cycle is shown to operate with a thermal efficiency approaching 46% for a turbine inlet temperature of 1400°C while producing about 1.5 kg of water for each kg of fuel (propane) consumed. The thermal efficiency does not take into account the cooling effect produced in the evaporator of VARS. The combined cycle efficiency at the above operating condition was found to be 49%. Low emissions are also possible on liquid fuels and not just on natural gas. It should be noted that the values of efficiencies obtained are for a medium sized engine with conservative values of the design parameters. It is observed that the largest contribution to the total cycle irreversibility comes from the combustor and accounts for 85% of the total exergy loss. The generator of the vapor absorption refrigeration system is the next largest quantity, accounting for about 3.4% of the total exergy loss. The mass of water extracted from the system increases as the value of the low-pressure compressor ratio is increased. However, this rate of increase is more when the compressor ratio is increased from 1.0 to 2.0 and less as the compressor ratio is further increased. Based on these and prior results, which showed that the HPRTE is very compact and has inherently low emissions, it appears that this cycle would be ideally suited for distributed power and vehicle applications, especially ones with associated air conditioning loads.

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Testing and Modeling of a Semi-Closed Gas Turbine Cycle Integrated With a Vapor Absorption Refrigeration System

Advanced Energy Systems ◽

10.1115/imece2006-15403 ◽

2006 ◽

Cited By ~ 3

Author(s):

J. R. Khan ◽

W. E. Lear ◽

S. A. Sherif ◽

E. B. Howell ◽

J. F. Crittenden ◽

...

Keyword(s):

High Pressure ◽

Combined Cycle ◽

Absorption Refrigeration ◽

Ambient Conditions ◽

Power Cycle ◽

High Pressure Compressor ◽

Refrigeration Unit ◽

Vapor Absorption ◽

Absorption Refrigeration System ◽

Vapor Absorption Refrigeration

A novel cooling and power cycle has been proposed that combines a semi-closed cycle gas turbine called the High Pressure Regenerative Turbine Engine (HPRTE) with a vapor absorption refrigeration system (VARS). The refrigeration cycle (VARS) interacts with the power cycle (HPRTE) solely through heat transfer in the generator and the evaporator. Waste heat from the recirculated combustion gas of the HPRTE is used to power the absorption refrigeration unit, which cools the high-pressure compressor inlet of the HPRTE to below ambient conditions and also produces excess refrigeration, in an amount which depends on ambient conditions. Water produced as a product of combustion is intentionally condensed in the evaporator of the VARS, which is designed to provide sufficient cooling for three purposes: chilling the inlet air to the high pressure compressor, water extraction, and for an external cooling load. In a previous study, the combined cycle was modeled using zero-dimensional steady-state thermodynamics, with the specified values of efficiencies and pressure drops for the turbo-machinery and heat exchangers. The model predicts that the combined cycle with steam blade cooling for a medium-sized engine will have a thermal efficiency of 49%, in addition to the external refrigeration load generated in the cycle which is 13% of the net work output. It also produces about 1.4 kg of water for each kg of fuel (propane) consumed. A small experimental unit demonstrating the HPRTE/VARS combined cycle has been constructed and is currently being tested in the Energy & Gas-dynamic Systems Laboratory at the University of Florida. A 45 HP Rover 1S-60 engine is integrated with a NH3/H2O vapor absorption refrigeration unit having a capacity of 19 Ton Refrigeration. The engine flow-path has been significantly modified to include partial recirculation of exhaust products, turbocharging, and recuperation, thus implementing the HPRTE concept. In addition, a significant modeling effort has been undertaken to simulate the combined cycle operation under design and off-design conditions. Initial experimental results show good agreement with the model predictions, including overall efficiency and water extraction rates.

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