Evaluation of annual operation cost of a combined system of ammonia absorption heat pump driven by low temperature waste heat and gas heat pump

As an effective energy-saving device, the heat pump is environmentally friendly and advantageous in the recovery of low-temperature and middle-temperature waste heat. So it is increasingly being used in practical applications. The circulating water which is produced by power plants has a large number of low-temperature waste heat. It will bring huge economic and environmental benefits by using heat pump technology to recover those waste heat energy. The application of the heat pump in supercritical unit is discussed as the example of central heating project using waste heat in a power plant. And the basic principle of absorption heat pump is introduced. The economy, energy conservation and environmental benefits of lithium bromide absorption heat pump are also analyzed when it is used in 600MW supercritical unit.

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Local Heating Networks with Waste Heat Utilization: Low or Medium Temperature Supply?

Energies ◽

10.3390/en13040954 ◽

2020 ◽

Vol 13 (4) ◽

pp. 954 ◽

Cited By ~ 1

Author(s):

Hanne Kauko ◽

Daniel Rohde ◽

Armin Hafner

Keyword(s):

Low Temperature ◽

Heat Pump ◽

Urban Areas ◽

Waste Heat ◽

Local Heating ◽

District Heating ◽

Heat Pumps ◽

Hot Water ◽

Local Network ◽

Medium Temperature

District heating enables an economical use of energy sources that would otherwise be wasted to cover the heating demands of buildings in urban areas. For efficient utilization of local waste heat and renewable heat sources, low distribution temperatures are of crucial importance. This study evaluates a local heating network being planned for a new building area in Trondheim, Norway, with waste heat available from a nearby ice skating rink. Two alternative supply temperature levels have been evaluated with dynamic simulations: low temperature (40 °C), with direct utilization of waste heat and decentralized domestic hot water (DHW) production using heat pumps; and medium temperature (70 °C), applying a centralized heat pump to lift the temperature of the waste heat. The local network will be connected to the primary district heating network to cover the remaining heat demand. The simulation results show that with a medium temperature supply, the peak power demand is up to three times higher than with a low temperature supply. This results from the fact that the centralized heat pump lifts the temperature for the entire network, including space and DHW heating demands. With a low temperature supply, heat pumps are applied only for DHW production, which enables a low and even electricity demand. On the other hand, with a low temperature supply, the district heating demand is high in the wintertime, in particular if the waste heat temperature is low. The choice of a suitable supply temperature level for a local heating network is hence strongly dependent on the temperature of the available waste heat, but also on the costs and emissions related to the production of district heating and electricity in the different seasons.

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Heat Integration of Absorption Heat Pump in a Milk Powder Dairy

10.1115/imece2000-1293 ◽

2000 ◽

Author(s):

Jens Møller Andersen

Keyword(s):

Heat Pump ◽

Waste Heat ◽

Cooling System ◽

Milk Powder ◽

Electricity Consumption ◽

Heat Pumps ◽

Heat Integration ◽

Absorption Heat Pump ◽

Absorption Cooling ◽

Absorption Cooling System

Abstract Heat integration with absorption heat pumps requires investigation of many types of plant designs. In this article, it is concluded that in many cases high temperature absorption systems for heat recovery are more economically feasible than absorption systems for cooling purposes. The conclusion is based on a project where the scope was to investigate technical and economical possibilities for heat integration of an absorption heat pump in a milk powder plant. The first idea behind the project was to use the waste heat from the rejected air to drive an absorption cooling system to reduce the electricity consumption for cooling proposes. The model of the plant was based on simulations as a background for a time averaged COP model. It was concluded that an absorption system for generating low temperature steam is more feasible.

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Thermodynamic and Exergoeconomic Analysis of a Supercritical CO2 Cycle Integrated with a LiBr-H2O Absorption Heat Pump for Combined Heat and Power Generation

Applied Sciences ◽

10.3390/app10010323 ◽

2020 ◽

Vol 10 (1) ◽

pp. 323 ◽

Cited By ~ 1

Author(s):

Yi Yang ◽

Zihua Wang ◽

Qingya Ma ◽

Yongquan Lai ◽

Jiangfeng Wang ◽

...

Keyword(s):

Heat Pump ◽

Supercritical Co2 ◽

Waste Heat ◽

Unit Cost ◽

Heating System ◽

Combined Heat And Power ◽

Economic Benefits ◽

Ammonia Water ◽

Absorption Heat Pump ◽

Comparison Results

In this paper, a novel combined heat and power (CHP) system is proposed in which the waste heat from a supercritical CO2 recompression Brayton cycle (sCO2) is recovered by a LiBr-H2O absorption heat pump (AHP). Thermodynamic and exergoeconomic models are established on the basis of the mass, energy, and cost balance equations. The proposed sCO2/LiBr-H2O AHP system is examined and compared with a stand-alone sCO2 system, a sCO2/DH system (sCO2/direct heating system), and a sCO2/ammonia-water AHP system from the viewpoints of energy, exergy, and exergoeconomics. Parametric studies are performed to reveal the influences of decision variables on the performances of these systems, and the particle swarm optimization (PSO) algorithm is utilized to optimize the system performances. Results show that the sCO2/LiBr-H2O AHP system can obtain an improvement of 13.39% in exergy efficiency and a reduction of 8.66% in total product unit cost compared with the stand-alone sCO2 system. In addition, the sCO2/LiBr-H2O AHP system performs better than sCO2/DH system and sCO2/ammonia-water AHP system do, indicating that the LiBr-H2O AHP is a preferable bottoming cycle for heat production. The detailed parametric analysis, optimization, and comparison results may provide some references in the design and operation of sCO2/AHP system to save energy consumption and provide considerable economic benefits.

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