Simulation analysis of performance optimization of gas-driven ammonia-water absorption heat pump

The generator-absorber heat exchange ammonia-water absorption heat pump has a relatively high efficiency and the COP is improved by recovering internal heat. In order to resolve the problem that generator-absorber heat exchange effect becomes less obvious or even fails under the working condition of large temperature lift, a novel system is proposed to recover the rectification heat and absorption heat by solution split method. Compared with the method of using total strong solution to recover absorption heat after extracting rectification heat, the method of solution split avoids the problem of high temperature of inlet strong solution of the solution cooled absorber, and improves the internal heat recovery capacity of the system. When using solution split method to recover the rectification heat and absorption heat, the solution split ratio K has an important influence on the system performance. This paper will theoretically study the selection range of the solution split ratio K and the effect of evaporation temperature, cooling water temperature and generation temperature on the optimum split ratio K. Compared to the system that uses the total strong solution to recover the rectification heat and absorption heat, the performance of the novel system is significantly improved, and the novel system performance coefficient can be increased by up to 15.7%.

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Thermodynamic Analysis of a Central Heating System Combing the Urban Heat Network With Geothermal Energy

ASME 2013 7th International Conference on Energy Sustainability ◽

10.1115/es2013-18285 ◽

2013 ◽

Author(s):

Xiao Wang ◽

Lin Fu ◽

Xiling Zhao ◽

Hua Liu

Keyword(s):

Heat Exchanger ◽

Heat Exchange ◽

Heat Pump ◽

Geothermal Energy ◽

Heating System ◽

Heat Network ◽

Pump System ◽

Absorption Heat Pump ◽

Central Heating ◽

Exchange Unit

In recent years, with the continuous urban expansion, the central heating sources are commonly insufficient in the areas of Northern China. Besides, the increasing heat transfer temperature difference results in more and more exergy loss between the primary heat network and the secondary heat network. This paper introduces a new central heating system which combines the urban heat network with geothermal energy (CHSCHNGE). In this system, the absorption heat exchange unit, which is composed of an absorption heat pump and a water to water heat exchanger, is as alternative to the conventional water to water heat exchanger at the heat exchange station, and the doing work ability of the primary heat network is utilized to drive the absorption heat pump to extract the shallow geothermal energy. In this way, the heat supply ability of the system will be increased with fewer additional energy consumptions. Since the water after driving the absorption heat pump has high temperature, it can continue to heat the supply water coming from the absorption heat pump. As a result, the water of the primary heat network will be stepped cooled and the exergy loss will be reduced. In this study, the performance of the system is simulated based on the mathematical models of the heat source, the absorption heat exchange unit, the ground heat exchanger and the room. The thermodynamic analyses are performed for three systems and the energy efficiency and exergy efficiency are compared. The results show that (a) the COP of the absorption heat exchange unit is 1.25 and the heating capacity of the system increases by 25%, which can effectively reduce the requirements of central heating sources; (b) the PER of the system increases 14.4% more than that of the conventional co-generation central heating system and 54.1% more than that of the ground source heat pump system; (c) the exergy efficiency of the CHSCHNGE is 17.6% higher than that of the conventional co-generation central heating system and 45.6% higher than that of the ground source heat pump system.

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Development and demonstration of a compact ammonia–water absorption heat pump prototype with microscale features for space-conditioning applications

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2016.03.169 ◽

2016 ◽

Vol 102 ◽

pp. 557-564 ◽

Cited By ~ 24

Author(s):

Srinivas Garimella ◽

Christopher M. Keinath ◽

Jared C. Delahanty ◽

Dhruv C. Hoysall ◽

Marcel A. Staedter ◽

...

Keyword(s):

Water Absorption ◽

Heat Pump ◽

Ammonia Water ◽

Absorption Heat Pump

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Design and analysis of an ammonia-water absorption heat pump

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2019.114531 ◽

2020 ◽

Vol 165 ◽

pp. 114531 ◽

Cited By ~ 4

Author(s):

Nico Mirl ◽

Fabian Schmid ◽

Bernd Bierling ◽

Klaus Spindler

Keyword(s):

Water Absorption ◽

Heat Pump ◽

Ammonia Water ◽

Absorption Heat Pump

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Compact Diesel Engine Waste-Heat Driven Ammonia-Water Absorption Heat Pump Modeling and Performance Maximization Strategies

Journal of Energy Resources Technology ◽

10.1115/1.4051804 ◽

2021 ◽

pp. 1-28

Author(s):

Christopher M. Keinath ◽

Jared Delahanty ◽

Srinivas Garimella ◽

Michael A. Garrabrant

Keyword(s):

Heat Exchanger ◽

Water Absorption ◽

Heat Pump ◽

Waste Heat ◽

Cooling Capacity ◽

Operating Conditions ◽

Heat Transfer Fluid ◽

Ammonia Water ◽

Absorption Heat Pump ◽

Wide Range

Abstract An investigation of the best ways to achieve optimal performance from a waste-heat-driven ammonia-water absorption heat pump over a wide range of operating conditions is presented. Waste-heat is recovered using an exhaust gas heat exchanger and delivered to the desorber by a heat transfer fluid loop. The absorber and condenser are hydronically coupled in parallel to an ambient heat exchanger for heat rejection. The evaporator provides chilled water for space-conditioning with a baseline cooling capacity of 2 kW. A detailed thermodynamics model is developed to simulate performance and develop strategies to achieve the best performance in both cooling and heating modes over a range of operating conditions. These parametric studies show that improved coefficients of performance can be achieved by adjusting the coupling fluid temperatures in the evaporator and the condenser/absorber as the ambient temperature varies. With the varying return temperatures, the system is able to provide the 2 kW design cooling capacity for a wide range of ambient temperatures.

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