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 Analysis of Heat Exchange Rate for Low-Depth Modular Ground Heat Exchanger through Real-Scale Experiment

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1893
Author(s):  
Kwonye Kim ◽  
Jaemin Kim ◽  
Yujin Nam ◽  
Euyjoon Lee ◽  
Eunchul Kang ◽  
...  
Keyword(s):  
Exchange Rate ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Heat Pump ◽  
Heat Extraction ◽  
Ground Heat Exchanger ◽  
Pump System ◽  
Heat Pump System ◽  
Scale Experiment ◽  
Real Scale

A ground source heat pump system is a high-performance technology used for maintaining a stable underground temperature all year-round. However, the high costs for installation, such as for boring and drilling, is a drawback that prevents the system to be rapidly introduced into the market. This study proposes a modular ground heat exchanger (GHX) that can compensate for the disadvantages (such as high-boring/drilling costs) of the conventional vertical GHX. Through a real-scale experiment, a modular GHX was manufactured and buried at a depth of 4 m below ground level; the heat exchange rate and the change in underground temperatures during the GHX operation were tracked and calculated. The average heat exchanges rate was 78.98 W/m and 88.83 W/m during heating and cooling periods, respectively; the underground temperature decreased by 1.2 °C during heat extraction and increased by 4.4 °C during heat emission, with the heat pump (HP) working. The study showed that the modular GHX is a cost-effective alternative to the vertical GHX; further research is needed for application to actual small buildings.

Experimental Study of Heating-Cooling Combined Ground Source Heat Pump System with Horizontal Ground Heat Exchanger

2011 ◽  
Vol 374-377 ◽  
pp. 398-404 ◽  
Author(s):  
Ying Ning Hu ◽  
Ban Jun Peng ◽  
Shan Shan Hu ◽  
Jun Lin
Keyword(s):  
Heat Exchanger ◽  
Heat Exchange ◽  
Heat Pump ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Ground Heat Exchanger ◽  
Pipe Length ◽  
Pump System ◽  
Heat Pump System ◽  
Heating And Cooling

A hot-water and air-conditioning (HWAC) combined ground sourse heat pump(GSHP) system with horizontal ground heat exchanger self-designed and actualized was presented in this paper. The heat transfer performance for the heat exchanger of two different pipe arrangements, three layers and four layers, respectively, was compared. It showed that the heat exchange quantity per pipe length for the pipe arrangement of three layers and four layers are 18.0 W/m and 15.0 W/m. The coefficient of performance (COP) of unit and system could remain 4.8 and 4.2 as GSHP system for heating water, and the COP of heating and cooling combination are up to 8.5 and 7.5, respectively. The power consumption of hot-water in a whole year is 9.0 kwh/t. The economy and feasibility analysis on vertical and horizontal ground heat exchanger were made, which showed that the investment cost per heat exchange quantity of horizontal ground heat exchanger is 51.4% lower than that of the vertical ground heat exchanger, but the occupied area of the former is 7 times larger than the latter's.

scholarly journals Frosting Phenomenon and Frost-Free Technology of Outdoor Air Heat Exchanger for an Air-Source Heat Pump System in China: An Analysis and Review

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2642 ◽  
Author(s):  
Yi Zhang ◽  
Guanmin Zhang ◽  
Aiqun Zhang ◽  
Yinhan Jin ◽  
Ruirui Ru ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Operating Cost ◽  
Heating System ◽  
Coefficient Of Performance ◽  
Outdoor Air ◽  
Pump System ◽  
Heat Pump System ◽  
Reduce Operating Cost ◽  
Air Source Heat Pump

Frost layer on the outdoor air heat exchanger surface in an air-source heat pump (ASHP) can decrease the system coefficient of performance (COP). Although the common defrosting and anti-frosting methods can improve the COP, the periodic defrosting not only reduces the system energy efficiency but also deteriorates the indoor environment. To solve these problems, it is necessary to clearly understand the frosting phenomenon and to achieve the system frost-free operation. This paper focused firstly on the analyses of frosting pathways and frosting maps. Followed by summarizing the characteristics of frost-free technologies. And then the performances of two types of frost-free ASHP (FFASHP) systems were reviewed, and the exergy and economic analysis of a FFASHP heating system were carried out. Finally, the existing problems related to the FFASHP technologies were proposed. Results show that the existing frosting maps need to be further improved. The FFASHP systems can not only achieve continuous frost-free operation but reduce operating cost. And the total COP of the FFASHP heating system is approximately 30–64% higher than that of the conventional ASHP system under the same frosting conditions. However, the investment cost of the FFASHP system increases, and its reliability also needs further field test in a wider frosting environment. In the future, combined with a new frosting map, the control strategy for the FFASHP system should be optimized.

The Matching Research of Soil Source Heat Pump and Central Heating System in Cold Region

2013 ◽  
Vol 805-806 ◽  
pp. 486-491
Author(s):  
Yue Ren Wang ◽  
Yu Feng Jiang ◽  
Min Yu
Keyword(s):  
Heat Pump ◽  
Heat Load ◽  
Working Condition ◽  
Heating System ◽  
Cold Region ◽  
Pump System ◽  
Heat Pump System ◽  
Heating Systems ◽  
Central Heating ◽  
Practical Engineering

Using Dest software simulation benchmark building the dynamic heat load, analyzing its distribution pattern, at the same timewe can also get heat pump units in the COP value is different under different working condition, then the soil source heat pump and central heating complementary heating system, undertake in soil source heat pump system design heat load, under theconditions of different proportion of the whole system operation energy consumption, initial investment analysis, we conclude thatthe soil source heat pump and central heating complementary heating systems of different energy matching optimization features,this provides a reference for practical engineering.

scholarly journals Analysis and Research on Energy-Saving Reconstruction of Building Heating System

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Yongqiang Liu ◽  
Zhanfang Huang
Keyword(s):  
Heat Source ◽  
Heat Pump ◽  
Original System ◽  
Water Source ◽  
Heating System ◽  
High Energy ◽  
Pipe Network ◽  
Pump System ◽  
Heat Pump System ◽  
Central Heating

A building heating system had high energy consumption and did not meet the requirements of environmental protection, so it was needed to be reformed. After recalculating the heat load, it was found that the heat source, pipe network specification, and radiator area of the original heating system were oversized. After comparing with a gas-fired boiler, the heat source was transformed into the water source heat pump system. The water supply temperature of the water source heat pump was lower than that of the boiler. Generally, it seemed necessary to increase the radiator area. However, after calculation and verification, when the supply and return water temperature was 65/58°C, the system operated continuously and the original pipe network and radiator could still ensure the indoor temperature of 16°C. The total cost of transformation was 11.5 million Chinese Yuan. After analyzing the operation data of the new system, the water source heat pump system could save 82.6% energy compared with the original system and 29.6% cost compared with the central heating system. The transformation is successful, and the experience is worth popularizing.

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

scholarly journals Performance evaluation of a novel PVT-GSHP heating system on energy-efficient poultry houses: long-term monitoring

2020 ◽  
Author(s):  
Tugba Gurler ◽  
Theo Elmer ◽  
Yuanlong Cui ◽  
Siddig Omer ◽  
Saffa Riffat
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Heating System ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Solar Pv ◽  
Pump System ◽  
Poultry House ◽  
Poultry Houses

Abstract The case study presented in this paper is an innovative ground source heat pump (GSHP) system constituted by a hybrid Photovoltaic Thermal (PVT) solar system for poultry houses. Farmers tend to not to apply GSHPs because of the high prices of excavation and time consumption. The innovative heat pump system assessed in this study comprises of a new type of heat exchangers; a thin-tube solar polyethylene heat exchanger installed between roof tiles and PV panels and a novel vertical ground heat exchanger to utilize the heat stored in the soil. The heating system applied to a poultry house are monitored and evaluated under a variety of environmental and operating conditions to achieve annual/long-term efficiency of the heating system in Kirton, UK. The maximum heating demand of the poultry house is determined 34.4 MWh/PC while the minimum is 11,1 MWh/PC. The monitored results show that the heat pump produced 15.02 MWh of thermal energy per annum. Solar PV and heat pump worked very well together with solar PV covering all the heat pump’s annual electrical energy requirement and generated 8.74 MWh of extra electricity exported to the grid. The seasonal coefficient of performance is found 3.73 through a year. The novel PVT-GSHP heating system is a very promising solution for high fossil fuel consumption in the agriculture industry and the energy savings of the whole system can be noticeably increased dependent up on the system controlling.

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.

Numerical Solution of a Ground Source Heat Pump System Using Foundation Piles

2013 ◽  
Author(s):  
Masahito Oguma ◽  
Takeshi Matsumoto ◽  
Ayako Funabiki ◽  
Futoshi Miyaoka ◽  
Kosuke Ito ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Exchange ◽  
Heat Pump ◽  
Arbitrary Sequence ◽  
Two Dimensional ◽  
Ground Source Heat Pump ◽  
Pump System ◽  
Heat Pump System ◽  
Ground Source ◽  
The Cost

A ground source heat pump (GSHP) system has higher cooling and heating performances than an air source heat pump system, so the GSHP system has attracted attention in the cold regions. Particularly after the 2011 earthquake off the Pacific coast of Tohoku, which damaged nuclear power plants, the GSHP utilizing renewable energy, has become attractive in heating system in the Tohoku region. However, it is necessary to install wells to collect ground source heat, and so, together with the cost of the heat pump itself, the installation cost is a barrier to widespread adoption of this technology in Japan. On the other hand, due to poor subsoil, foundation piles are often required in the construction of buildings in Japan. By using foundation piles as heat exchangers, which are commonly used in residential construction, the cost of using GSHP systems in houses may be reduced. However, since the placement of the piles depends on the floor layout of the residence, that is arbitrary sequence. Moreover, an arbitrary floor layout requires a complicated multi-dimensional numerical analysis to design the GSHP, and the analysis is burdensome for general designers. Therefore, the use of the model unit of the two-dimensional cylindrical heat exchange well is proposed. The use of this model, which includes an unused volume of soil, reduces the analysis burden for general design tools. On experience, the arrangement rate is 4 m2 per pile, and the well separation is narrow. And the foundation piles will form a group. So thermal interference between heat exchanger wells might be working hard. In addition, the foundation piles are very short, compared to the traditional borehole depth of 50 to 100 m. Therefore, the thermal performance of the well may degrade compared to that of the traditional GSHP system, although the initial costs are less. Therefore, we examined a GSHP system with heat exchanger piles by using the heat exchange well unit model for residences in the Tohoku region. As a result, the two-dimensional analysis and more is needed to predict the thermal performances of the heat exchanger piles so that the effect of the pitch of the heat exchange wells on the heat transfer in the axial direction will be large. In cold climates, the heating demand is large and, in the summer, the amount of waste heat to the ground is small, so a large amount of heat penetration into the ground from the atmospheric air is important for continuous GSHP operation in the Tohoku region, and in Fukushima Prefecture in particular.

scholarly journals Feasibility Study of Ground Source Heat Pump System Considering Underground Thermal Properties

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1786 ◽  
Author(s):  
Sang Mu Bae ◽  
Yujin Nam ◽  
Byoung Ohan Shim
Keyword(s):  
Exchange Rate ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Heat Pump ◽  
Geothermal Gradient ◽  
Soil Conditions ◽  
Ground Source Heat Pump ◽  
Pump System ◽  
Heat Pump System ◽  
Ground Source

: A typical ground source heat pump (GSHP) system in South Korea has a ground heat exchanger (GHX) with a length of 100–150 m, which utilizes annually stable underground temperature to meet the loads of cooling, heating and hot water in buildings. However, most GSHP systems have been introduced in heating dominated areas because the system performance advantage is larger compared with air source heat pump system than that in cooling dominated areas. To effectively provide geothermal energy to the building in the limited urban area, it is necessary to install deep GHXs. Despite its large capacity, there are few studies on GSHP system with deep GHX over 300 m. In this study, to estimate the performance of the GSHP system with deep GHX and evaluate its feasibility, numerical simulation was conducted. To quantitatively analyze heat transfer between soil and GHX, the coupled model with GHX model and ground heat and groundwater transfer model was used. Furthermore, the heat exchange rate and the source temperature were calculated according to the operation modes, the length of GHX, and soil conditions such as geothermal gradient and thermal conductivity. As a result, the total heat exchange rate of GHX with a length of 300 m heat exchanger was 12.62 kW, 173% that of a length of 150 m. Finally, it was found that the GSHP system with deep GHX has realistic possibility in good condition of geothermal gradient.

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