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

2020 ◽  
Vol 10 (1) ◽  
pp. 323 ◽  
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.

Exergoeconomic Analysis of New High-Temperature District Heating System Based on Absorption Heat Pump Technology in Combined Heat and Power

2010 ◽  
Author(s):  
Fangtian Sun ◽  
Lin Fu ◽  
Shigang Zhang
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Waste Heat ◽  
District Heating ◽  
Heating System ◽  
Combined Heat And Power ◽  
Space Heating ◽  
Exergetic Efficiency ◽  
District Heating System ◽  
Absorption Heat Pump

Space heating area of district heating system of combined heat and power (CHP) accounts for approximately one third of total space heating area in Chinese northern cities. In the extraction condensing turbine combined heat and power system based on district heating network, there are a large number of low-grade waste heat in the condenser, and exergy loss in the steam-water heat exchanger and water-water heat exchanger. Based on absorption heat pump technology, a new high-temperature district heating technology (DHSAHP) was presented to improve the current district heating system of CHP. Absorption heat pumps are used to recycle low-temperature waste heat in condenser. Absorption heat pump type heat exchanger is used to reduce temperature of return water in primary heat network, and decrease irreversible loss. Where, DHSAHP was analyzed by thermodynamics and economics method, and evaluated by exergetic efficiency, exergetic output cost, exergetic cost difference and exergoeconomic factor. Compared with current district heating system of CHP, DHSAHP can decrease about 31.3% steam consumption, increase about 75% transmission and distribution capacity of the primary heating network. The evaluation results show that the exergetic efficiency of new district heating system of CHP based on the absorption cycle technology is higher 10.41% than that of current district heating system of CHP, whereas its exergetic cost is lower 36.6¥/GJ than that of the conventional district heating system. With the increase of annual heating time, economy efficiency of new district heating system of CHP becomes better. The DHSAHP has higher energy utilization efficiency and better economic benefits and provides a kind of better technological method to solve the main problems of cuurent district heating with CHP in China.

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

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.

Application of Heat Pump Water Heating System with Heat Recovery in Ammonia Refrigeration System

2012 ◽  
Vol 614-615 ◽  
pp. 670-673
Author(s):  
Tao Huang ◽  
Dong Li Yuan
Keyword(s):  
Heat Pump ◽  
Heat Recovery ◽  
Waste Heat ◽  
Recovery Period ◽  
Operating Cost ◽  
Heating System ◽  
Economic Benefits ◽  
Refrigeration System ◽  
Operating Characteristics ◽  
Water Heating

In this paper, a heat pump water heating system with waste heat recovery in ammonia refrigeration system was put forward, based on the practical project analysis of energy demand and waste heat emission. Based on the operating characteristics of ammonia refrigeration system, the ammonia heat exchanger was designed to be installed in series on the ammonia main pipe, which can ensure the system operate efficiently and reliably. Through the analysis of measured data, significant economic benefits had been brought about by using the heat pump water heating system. This project can save 2.19 million RMB in annual operating cost, and the investment recovery period will be only 1.5 years. The heat pump water heating system has excellent development prospect.

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

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.

scholarly journals Modified High Back-Pressure Heating System Integrated with Raw Coal Pre-Drying in Combined Heat and Power Unit

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2487 ◽  
Author(s):  
Heng Chen ◽  
Zhen Qi ◽  
Qiao Chen ◽  
Yunyun Wu ◽  
Gang Xu ◽  
...  
Keyword(s):  
Power Generation ◽  
Flue Gas ◽  
Waste Heat ◽  
Heating System ◽  
Combined Heat And Power ◽  
Back Pressure ◽  
Coal Consumption ◽  
Heating Capacity ◽  
Boiler Efficiency ◽  
Saving Effect

A conceptual high-back pressure (HBP) heating system cooperating raw coal pre-drying for combined heat and power (CHP) was proposed to improve the performance of the HBP-CHP unit. In the new design, besides of heating the supply-water of the heating network, a portion of the exhaust steam from the turbine is employed to desiccate the raw coal prior to the coal pulverizer, which further recovers the waste heat of the exhaust steam and contributes to raising the overall efficiency of the unit. Thermodynamic and economic analyzes were conducted based on a typical 300 MW coal-fired HBP-CHP unit with the application of the modified configuration. The results showed that the power generation thermal efficiency promotion of the unit reaches 1.7% (absolute value) owing to suggested retrofitting, and meanwhile, the power generation standard coal consumption rate is diminished by 5.8 g/kWh. Due to the raw coal pre-drying, the energy loss of the exhaust flue gas of the boiler is reduced by 19.1% and the boiler efficiency increases from 92.7% to 95.4%. The impacts of the water content of the dried coal and the unit heating capacity on the energy-saving effect of the new concept were also examined.

Experience With a Solar Heating ATES System for a University Building

1994 ◽  
Vol 116 (2) ◽  
pp. 88-93 ◽  
Author(s):  
E. Hahne ◽  
M. Hornberger
Keyword(s):  
Solar Energy ◽  
Heat Pump ◽  
Waste Heat ◽  
Heating System ◽  
Solar Heating ◽  
Coefficient Of Performance ◽  
Solar Collectors ◽  
Power Station ◽  
Heat Demand ◽  
Heat Store

At Stuttgart University, a solar heating system for an office building with laboratories and lecture rooms was installed in 1985. It consists of 211 m2 of unglazed solar collectors, a 1050 m3 water-flooded pebble bed heat store, and a heat pump. Heat can be supplied to the store from the solar collectors or from a power station (as waste heat). The whole system has worked successfully for five years under varied strategies. In the first two heating periods, the heating strategy was aimed to collect as much solar energy as possible. Thus, about 60 percent of the heat demand could be covered by solar energy; but the yearly heat pump coefficient of performance (COP) was only around 2.76. With an improved heat pump, a monthly COP of 3.6 was obtained. Heat losses from the storage amounted to about 20 percent.

Heat Integration of Absorption Heat Pump in a Milk Powder Dairy

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.

scholarly journals The application of the TES technology in CHP heating system with Chinese demand profiles——A techno-economic feasibility case study

2019 ◽  
Vol 111 ◽  
pp. 06010
Author(s):  
Ruoyu Zhang ◽  
Haichao Wang ◽  
Xiaozhou Wu ◽  
Xiangli Li ◽  
Lin Duanmu
Keyword(s):  
Mathematical Model ◽  
Heating System ◽  
Combined Heat And Power ◽  
Economic Benefits ◽  
Economic Feasibility ◽  
Electricity Pricing ◽  
Peak Shaving ◽  
Optimum Type ◽  
Chp System

The thermal energy storage (TES) technology is an effective method to enhance the planning and the economy of the combined heat and power (CHP) plants, while it has still not been broadly promoted in China. In this paper we firstly establish a mathematical model for a Chinese CHP plant with TES. Then the EnergyPRO software is used to find the optimum type of the TES tank in a three-tariff electricity pricing market and the operation strategy of the CHP plant with the selected TES tank is studied. Thirdly, the economic benefits of the system with/without TES is evaluated. The results show that adding a TES tank with volume of 24000m3 can significantly increase operational profits of the CHP system and reduce the use of peak-shaving heat source.

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