scholarly journals Exergy analysis of the performance of low-temperature district heating system with geothermal heat pump

2014 ◽  
Vol 35 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Robert Sekret ◽  
Anna Nitkiewicz
Keyword(s):  
Heat Exchanger ◽  
Low Temperature ◽  
Heat Pump ◽  
Exergy Analysis ◽  
Heating System ◽  
Total System ◽  
Exergy Destruction ◽  
Geothermal Heat ◽  
District Heating System ◽  
Absorption Heat Pump

Abstract Exergy analysis of low temperature geothermal heat plant with compressor and absorption heat pump was carried out. In these two concepts heat pumps are using geothermal water at 19.5 oC with spontaneous outflow 24 m3/h as a heat source. The research compares exergy efficiency and exergy destruction of considered systems and its components as well. For the purpose of analysis, the heating system was divided into five components: geothermal heat exchanger, heat pump, heat distribution, heat exchanger and electricity production and transportation. For considered systems the primary exergy consumption from renewable and non-renewable sources was estimated. The analysis was carried out for heat network temperature at 50/40 oC, and the quality regulation was assumed. The results of exergy analysis of the system with electrical and absorption heat pump show that exergy destruction during the whole heating season is lower for the system with electrical heat pump. The exergy efficiencies of total system are 12.8% and 11.2% for the system with electrical heat pump and absorption heat pump, respectively.

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.

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 Some Problems of the Integration of Heat Pump Technology into a System of Combined Heat and Electricity Production

10.14311/212 ◽  
2001 ◽  
Vol 41 (2) ◽  
Author(s):  
G. Böszörményi ◽  
L. Böszörményi
Keyword(s):  
Heat Pump ◽  
District Heating ◽  
Heating System ◽  
Energy Utilization ◽  
Electricity Production ◽  
Geothermal Heat ◽  
District Heating System ◽  
Thermal Output ◽  
Short Period

The closure of a part of the municipal combined heat and power (CHP) plant of Košice city would result in the loss of 200 MW thermal output within a realtively short period of time. The long term development plan for the Košice district heating system concentrates on solving this problem. Taking into account the extremely high (90 %) dependence of Slovakia on imported energy sources and the desirability of reducing the emission of pollutantst the alternative of supplying of 100 MW thermal output from geothermal sources is attractive. However the indices of economic efficiency for this alternative are unsatisfactory. Cogeneration of electricity and heat in a CHP plant, the most efficient way of supplying heat to Košice at the present time. If as planned, geothermal heat is fed directly into the district heating network the efficiency would be greatly reduced. An excellent solution of this problem would be a new conception, preferring the utilization of geothermal heat in support of a combined electricity and heat production process. The efficiency of geothermal energy utilization could be increased through a special heat pump. This paper deals with several aspects of the design of a heat pump to be integrated into the system of the CHP plant.

scholarly journals Performance analysis of a solar heating system with the absorption heat pump and oil/water heat exchanger

2017 ◽  
Vol 142 ◽  
pp. 97-104 ◽  
Author(s):  
Man Fan ◽  
Hongbo Liang ◽  
Shijun You ◽  
Huan Zhang ◽  
Baoquan Yin ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Performance Analysis ◽  
Heat Pump ◽  
Heating System ◽  
Solar Heating ◽  
Absorption Heat Pump ◽  
Oil Water

Thermodynamic Evaluation of a Direct Expansion Ground-Sourced Heat Pump with Horizontal Ground Heat Exchangers Using Advanced Exergy Analysis

2021 ◽  
Author(s):  
Abdolazim Zarei ◽  
Mehran Ameri ◽  
Hossein Ghazizade-Ahsaee
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Exergy Analysis ◽  
Thermodynamic Evaluation ◽  
Ground Heat Exchanger ◽  
Exergy Destruction ◽  
Direct Expansion ◽  
Expansion Valve ◽  
System Improvement

This paper deals with the advanced exergetic analysis of a horizontal direct-expansion ground sourced CO2 heat pump operating in a transcritical cycle. The cycle is thermodynamically modeled in Engineering Equation Solver (EES) considering the pressure drops in both high and low temperature heat exchangers, and the system is to provide a fixed heating load. Conventional exergy analysis orderly suggests a compressor, expansion valve, gas cooler and ground heat exchanger to be considered for system improvement, while tracing exergy destruction of all components in detail demonstrates true improvement potential of each and all components and the system as a whole and offers a different order. Advanced exergy analysis points out that the compressor is directly and indirectly responsible for 56% of the overall exergy destruction generated in the cycle, confirming the detrimental role of this component in the system. The second influential component is recognized to be a ground heat exchanger accounting for 20% exergy destruction of the compressor as well as submitting 89% avoidability in its own exergy destruction, and expansion valve proves to be the last option for system improvement according to this analysis.

Cogeneration unit with an absorption heat pump for the district heating system

2014 ◽  
Vol 20 (4) ◽  
pp. 404-410 ◽  
Author(s):  
Agnese Lickrastina ◽  
Normunds Talcis ◽  
Egils Dzelzitis
Keyword(s):  
Heat Pump ◽  
District Heating ◽  
Heating System ◽  
District Heating System ◽  
Absorption Heat Pump
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