The Experts below are selected from a list of 5517 Experts worldwide ranked by ideXlab platform
Mengjie Song - One of the best experts on this subject based on the ideXlab platform.
-
techno economic analysis on frosting defrosting operations for an air source Heat Pump Unit with an optimized multi circuit outdoor coil
Energy and Buildings, 2018Co-Authors: Mengjie Song, Christopher Yu Hang Chao, Chili WuAbstract:Abstract Air source Heat Pump (ASHP) Units are used in applications around the world. After optimizing the multi-circuit outdoor coil by installing water collecting trays between circuits and adjusting the refrigerant distribution by using valves located at each circuit, system frosting/defrosting operation performances could be effectively improved. Before practical industry-scale application of trays and valves, their economic performances should be evaluated. However, in current literature, techno-economic analysis on operation performance of ASHP Units is rare, which limits the development of innovative technologies. Therefore, a techno-economic analysis on frosting/defrosting operations is carried out in this study. Firstly, the frosting/defrosting experiments are introduced, followed by a series of assumptions and calculations. Then, the economic analysis results are provided in detail. Compared with a traditional ASHP Unit, the total running costs of the modified Unit in the Heating season could save as much as 3681.75 CNY, or 10.33%, and the total cost decreased by 3516.75 CNY, or 4.67%, over 15 years of service life. The payback period of the additional initial cost is less than 8 months. Contribution of this work plays an important role in the evaluation and application of new technologies in the HVAC field.
-
techno economic analysis on frosting and defrosting operations of an air source Heat Pump Unit applied in a typical cold city
Energy and Buildings, 2018Co-Authors: Mengjie Song, Kai WangAbstract:Abstract In recent years, air source Heat Pump (ASHP) Units have found applications worldwide due to their advantages. For an ASHP Unit with a multi-circuit outdoor coil, when the refrigerant distribution adjusted with the valves, system defrosting efficiency could be optimized. Meanwhile, adjusting the refrigerant distribution by using valves located at each circuit could improve the frosting evenness value, and system coefficient of performance and the defrosting efficiency are thereby both optimized. However, in open literature, no tech-economic analysis work on frosting/defrosting performances of ASHP Units is reported, which limits the development of innovation technologies in this field. Therefore, a techno-economic analysis on frosting/defrosting operations for an ASHP Unit used in typical cold regions is given, basing on previous experimental work and series of assumptions. As concluded, the total running costs of the new ASHP Unit could decrease as much as 5,327.99 CNY ($ 798.87), or 7.67%, and the total cost about 5,177.99 CNY ($ 776.36), or 6.68%, in 15 years’ service life, compared with a traditional one. The payback period of additional first cost of valves is less than 1 year. Conclusions of this study might provide a new analytical tool for scholars, researchers, product developers, and policy designers, and shed new light on the designing and performance optimization of ASHP Units.
-
field test and numerical investigation on the Heat transfer characteristics and optimal design of the Heat exchangers of a deep borehole ground source Heat Pump system
Energy Conversion and Management, 2017Co-Authors: Zhihua Wang, Fenghao Wang, Mengjie SongAbstract:Abstract Deep borehole ground source Heat Pump (DBGSHP) is a new type of Heat Pump Heating system which extracts deep geothermal energy through Heat exchange and can be applied for space Heating in winter. To date, the development of deep borehole Heat exchangers (BHEs) is limited to the cognized structure design and there is a lack of the experimental studies. This paper presents the investigation of the Heat transfer characteristics of the Heat exchanger of a DBGSHP Heating system through both field test and numerical simulation. A field test was first carried out based on the DBGSHP implemented in a demonstration project. A numerical model was then developed to facilitate the evaluation of the Heat extraction capacity and the outlet temperature of the coaxial deep BHEs. Based on the numerical model developed, a sensitivity study was further performed to examine the effect of the primary parameters including the inlet velocity, inlet temperature, flow pattern (one was that the circulating fluid flowed from the inner pipe to the annular space and the other was that the circulating fluid flowed from the annular space to the inner pipe) and pipe diameter on the performance of deep BHE. The results from the field test indicated that the average Heat transfer capacity of each single borehole, the average COP of the Heat Pump Unit and the DBGSHP Heating system COP were 286.4 kW, 6.4 and 4.6, respectively. The simulation results matched well with the field test data, and showed that the inlet fluid velocity between 0.3 m/s and 0.7 m/s as well as the circulating fluid flowed from the annular space to the inner pipe can result in a better performance for the system of concern. The results from this study could be used as a reference basis for optimal design of coaxial deep BHE and to promote the utilization of deep geothermal energy.
-
Experimental investigation on an air source Heat Pump Unit with a three-circuit outdoor coil for its reverse cycle defrosting termination temperature
Applied Energy, 2017Co-Authors: Mengjie Song, Guangcai Gong, Zhihua WangAbstract:Abstract Air source Heat Pump Units could efficiently recover low grade waste Heat from ambient air for indoor air Heating or hot water supplying, which makes them widely applied in recent decades. For a vertically installed multi-circuit outdoor coil, a reverse cycle defrosting operation is always used to solve its frosting problem at high humidity and cold climate. Reverse cycle defrosting operation is terminated when the tube surface temperature at exit of the lowermost circuit reaching a pre-set value. It is obviously that when the pre-set temperature is higher or lower, the defrosting duration would be prolonged or more residual water left, respectively. Both of them result in potential energy waste for an air source Heat Pump Unit, or even adversely degrade the indoor thermal comfort. However, as reported, a wide range of 10–35 °C was used as the pre-set defrosting termination temperature, without a fixed value or range given. To save energy for an air source Heat Pump Unit, in this paper, an experimental methodology was firstly presented. Then, an air source Heat Pump Unit with three-circuit outdoor coil was specially selected, and experimental investigation conducted. Finally, the defrosting termination temperature was concluded suitable at 20–25 °C, around 22 °C for this study. This methodology makes contributions to the control strategy optimization and energy saving for air source Heat Pump Units.
-
numerical study on the operating performances of a novel frost free air source Heat Pump Unit using three different types of refrigerant
Applied Thermal Engineering, 2017Co-Authors: Zhihua Wang, Fenghao Wang, Mengjie SongAbstract:Abstract Air-source Heat Pump (ASHP) is a promising device using in residential buildings because of its energy-savings. Besides, R134a and R407C as environmental friendly refrigerant have advantage to apply into Heat Pump system. In this study, an investigation of a novel frost-free ASHP system, integrated with dehumidification and thermal energy storage, working with R134a and R407C as an R22 alternative, was presented. A mathematical model of the system is constructed and verified by comparison with experimental data that shows the measured results are in good accordance with the numerical ones. According to the mathematical model, the dynamic performance of the system is characterized by dehumidification and regeneration efficiency, suction and discharge pressure, COP and so on at ambient temperature of 0 °C and RH (relatively humidity) of 85%. The results show that the time for keeping the evaporator frost-free operation for R22, R407C and R134a are 29, 34 and 35 minutes, respectively. In addition, at the end of working time, the discharge pressure of compressor for R134a is 29 and 32% lower than that for R22 and R407C. What is more, at the given ambient temperature of −10 °C and RH of 85%, the average COP for R134a is 3.3 and 8.6%, respectively, which is higher than that for R22 and R407C.
Arif Hepbasli - One of the best experts on this subject based on the ideXlab platform.
-
exergetic analysis and evaluation of a new application of gas engine Heat Pumps gehps for food drying processes
Applied Energy, 2011Co-Authors: Aysegul Gungor, Zafer Erbay, Arif HepbasliAbstract:In this study, three medicinal and aromatic plants (Foeniculum vulgare, Malva sylvestris L. and Thymus vulgaris) were dried in a pilot scale gas engine driven Heat Pump drier, which was designed, constructed and installed in Ege University, Izmir, Turkey. Drying experiments were performed at an air temperature of 45 °C with an air velocity of 1 m/s. In this work, the performance of the drier along with its main components is evaluated using exergy analysis method. The most important component for improving the system efficiency is found to be the gas engine, followed by the exhaust air Heat exchanger for the drying system. An exergy loss and flow diagram (the so-called Grassmann diagram) of the whole drying system is also presented to give quantitative information regarding the proportion of the exergy input dissipated in the various system components, while the sustainability index values for the system components are calculated to indicate how sustainability is affected by changing the exergy efficiency of a process. Gas engine, expansion valve and drying ducts account for more than 60% amount of exergy in the system. The exergetic efficiency values are in the range of 77.68-79.21% for the Heat Pump Unit, 39.26-43.24% for the gas engine driven Heat Pump Unit, 81.29-81.56% for the drying chamber and 48.24-51.28% for the overall drying system.
-
exergetic modeling and assessment of solar assisted domestic hot water tank integrated ground source Heat Pump systems for residences
Energy and Buildings, 2007Co-Authors: Arif HepbasliAbstract:Abstract The present study deals with the exergetic modeling and performance evaluation of solar assisted domestic hot water tank integrated ground-source Heat Pump (GSHP) systems for residences for the first time to the best of the author's knowledge. The model is applied to a system, which mainly consists of (i) a water-to-water Heat Pump Unit (ii) a ground Heat exchanger system having two U-boreholes with an individual depth of 90 m, (iii) a solar collector system composing of rooftop thermal solar collectors with a total surface area of 12 m 2 , (iv) a domestic hot water tank with a electrical supplementary Heater, and (v) a floor Heating system with a surface of 154 m 2 , and (vi) circulating Pumps. Exergy relations for each component of the system and the whole system are derived for performance assessment purposes, while the experimental and assumed values are utilized in the analysis. Exergy efficiency values on a product/fuel basis are found to be 72.33% for the GSHP Unit, 14.53% for the solar domestic hot water system and 44.06% for the whole system at dead (reference) state values for 19 °C and 101.325 kPa. Exergetic COP values are obtained to be 0.245 and 0.201 for the GSHP Unit and the whole system, respectively. The greatest irreversibility (exergy destruction) on the GSHP Unit basis occurs in the condenser, followed by the compressor, expansion valve and evaporator.
-
a study on modeling and performance assessment of a Heat Pump system for utilizing low temperature geothermal resources in buildings
Building and Environment, 2007Co-Authors: Arif Hepbasli, Tolga M BaltaAbstract:Abstract Low and moderate geothermal resources are found in most areas of the world. A very efficient way to Heat and air-condition homes and buildings is the utilization of ground source Heat Pumps (GSHPs), also known as geothermal Heat Pump (GHPs), to obtain Heat energy from low temperature geothermal resources. The present study deals with the modeling and performance evaluation of a Heat Pump system utilizing a low temperature geothermal resource, which is approximated to a geothermal reservoir. The system was designed, constructed and tested in Nigde University, Nigde, Turkey and has been successfully operated since 2005. Energy and exergy analysis methods were used to assess the system performance based on the experimental data. Exergy destructions (or irreversibilities) as well as energy and exergy efficiency relations were presented for each component of the Heat Pump Unit and the whole system, while some thermodynamic parameters, such as fuel depletion ratio, relative irreversibility, productivity lack, exergetic factor and improvement potential, were investigated for the system. Energy and exergy efficiency values on a product/fuel basis were found to range from 73.9% to 73.3% and 63.3% to 51.7% at dead (reference) state temperatures varying from 0 to 25 °C for the Heat Pump Unit and entire system, respectively. It is expected that the model presented here would be beneficial to the researchers, government administration, and engineers working in the area of Heat Pump systems for residential applications.
-
thermodynamic analysis of a ground source Heat Pump system for district Heating
International Journal of Energy Research, 2005Co-Authors: Arif HepbasliAbstract:This study deals with the thermodynamic analysis of ground-source Heat Pump (GSHP) systems for district Heating. The mass, energy, entropy and exergy balance relations are derived and applied to a GSHP system with a U-bend ground Heat exchanger. The performance characteristics of this GSHP system are evaluated in terms of energetic and exergetic aspects. Based on the measurements conducted on 7 January 2004, the Heat extraction rate from the soil is found to be, on average, 61.4 W m−1 of bore depth, while the required borehole length in meter per kW of Heating capacity is obtained as 11.71. The entering water temperature to the Unit is measured to be 15.3°C. The Heating coefficient of performance of the Heat Pump (COPHP) is about 2.85, while that for the whole system is obtained to be 7.4% lower than COPHP. The exergy efficiency values for the Heat Pump Unit and whole system are found to be 66.8 and 66.6%, respectively. Copyright © 2005 John Wiley & Sons, Ltd.
-
experimental performance analysis of a solar assisted ground source Heat Pump greenhouse Heating system
Energy and Buildings, 2005Co-Authors: Onder Ozgener, Arif HepbasliAbstract:Abstract Ground-source Heat Pumps (GSHPs), also known as geothermal Heat Pumps (GHPs), are recognized to be outstanding Heating, cooling and water Heating systems, and have been used since 1998 in the Turkish market. Greenhouses also have important economical potential in Turkey’s agricultural sector. In addition to solar energy gain, greenhouses should be Heated during nights and cold days. In order to establish optimum growth conditions in greenhouses, renewable energy sources should be utilized as much as possible. It is expected that effective use of Heat Pumps with a suitable technology in the modern greenhouses will play a leading role in Turkey in the foreseeable future. The main objective of the present study is to investigate to the performance characteristics of a solar assisted ground-source Heat Pump greenhouse Heating system (SAGSHPGHS) with a 50 m vertical 1 × 1/4 in. nominal diameter U-bend ground Heat exchanger using exergy analysis method. This system was designed and constructed in Solar Energy Institute of Ege University, Izmir, Turkey. The exergy transports between the components and the destructions in each of the components of the SAGSHPGHS are determined for the average measured parameters obtained from the experimental results. Exergetic efficiencies of the system components are determined in an attempt to assess their individual performances and the potential for improvements is also presented. The Heating coefficient of performances of the ground-source Heat Pump Unit and the overall system are obtained to be 2.64 and 2.38, respectively, while the exergetic efficiency of the overall system is found to be 67.7%.
Lin Duanmu - One of the best experts on this subject based on the ideXlab platform.
-
multifactor analysis on beach well infiltration intake system for seawater source Heat Pump
Energy and Buildings, 2017Co-Authors: Xin Jia, Lin Duanmu, Haiwen ShuAbstract:Abstract The seawater source Heat Pump (SWHP) is a renewable energy utilization system. The beach well infiltration intake system (BWIS) effectively improves the stability, reliability, and energy efficiency of SWHP systems in cold climate areas. BWIS research requires a multidisciplinary approach that involves both hydrogeology and Heat transfer theory. There are many factors influencing the energy consumption and life-cycle costs of the systems, with each factor having many possible values. This paper aims to determine the degree of influence of ten representative factors of BWIS: specific Heat capacity of rock-soil, rock-soil density, thermal conductivity of rock-soil, void fraction of rock-soil, rock-soil permeability, beach well radius, site length, site width, row number of beach wells, and column number of beach wells. In this paper, a BWIS seepage and Heat transfer model is established. Based on the model, an orthogonal design optimization method is presented and analyses are conducted for Heat Pump Unit energy consumption, seawater Pump energy consumption, and economic cost for various conditions using MATLAB code. The results indicate that a greater number of beach wells is not always better and the number and placement of beach wells should be scientifically and objectively optimized by the orthogonal design method. The optimization method can scientifically guide engineering design for BWIS and offset the design deficiency that results from the current practice of only using a hydrogeological report of randomly selected test wells.
-
energy efficiency enhancement potential of the Heat Pump Unit in a seawater source Heat Pump district Heating system
Procedia Engineering, 2016Co-Authors: Shu Hiawen, Wang Tingyu, Ren Zhiyong, Yu Haiyang, Lin DuanmuAbstract:Abstract Seawater source Heat Pump district Heating system is a renewable energy utilization system as it can utilize the sensible Heat energy contained in the seawater. The energy efficiency of the system is always the main concern for the system researchers. So a field measurement with an emphasis on the energy efficiency of an actual seawater source Heat Pump district Heating system was conducted, and the energy efficiency enhancement potential of the Heat Pump Unit was analyzed and evaluated. The measurement showed that the Heat Pump Units consumed the largest part of energy consumption of the whole system, and the coefficient of Heating performance (COP) of the seawater source Heat Pump Units was quite low especially during the coldest measurement period which was only 2.43. In the light of the concept of Thermodynamic Perfectibility, the energy efficiency enhancement potential of the Heat Pump Unit was carefully analyzed and calculated. And the results showed that there is about an average of 24.2% energy efficiency enhancement potential of the Heat Pump Units in this project.
-
field measurement and energy efficiency enhancement potential of a seawater source Heat Pump district Heating system
Energy and Buildings, 2015Co-Authors: Lin Duanmu, Haiyang YuAbstract:Abstract As a renewable energy utilization system, seawater source Heat Pump district Heating system can eliminate the local air pollution compared with the direct combustion of fuel in the conventional boiler house district Heating system in northern cold climate area. A field measurement with an emphasis on the energy efficiency of an actual seawater source Heat Pump district Heating system was conducted and analyzed. The field measurement showed that the Heat Pump Units consumed the largest part of energy consumption of the whole system (as high as 78.9% in the project). However, the coefficient of Heating performance (COP) of the seawater source Heat Pump Unit was as low as 2.43. Then the energy efficiency enhancement potential of the Heat Pump Unit was carefully analyzed and calculated in the light of the index of Thermodynamic Perfectibility for the Heat Pump Unit. And the results showed that there is about an average of 24.2% energy efficiency enhancement potential of the Heat Pump Units in the project. In the end, a verification case study indicated that the COP of the Heat Pump Units in the project will increase 34.6% if they are substituted by the ones made by another manufacturer.
-
experimental performance analysis of a solar assisted ground source Heat Pump system under different Heating operation modes
Applied Thermal Engineering, 2015Co-Authors: Sufen Li, Lin Duanmu, Xiangli Li, Yan Shang, Ming DongAbstract:Abstract This paper presents an experimental study on the influence of operation modes on the Heating performance of a solar assisted ground source Heat Pump system (SAGSHPS). Through experiments conducted in January, the characteristics of the SAGSHPS were investigated under different Heating operation modes. The results indicate that the solar thermal could be used to accelerate the soil recovery when the Heat Pump Unit is turned off, but the duration of solar use to recharge boreholes should be optimized according to the water temperature in the solar Heat storage water tank to avoid unnecessary power consumption of the circulation Pump. In addition, the solar Heat storage water tank is beneficial for the stable operation of the SAGSHPS. The volumetric flow rate in the water tank has a significant impact on the electricity consumption of the SAGSHPS. From comprehensive analysis of the integral effect of the SAGSHPS under different modes, the mode in which the water tank is connected with the ground Heat exchangers (GHES) in series is the recommended mode for the SAGSHPS in the coldest month in Dalian.
Zhihua Wang - One of the best experts on this subject based on the ideXlab platform.
-
field test and numerical investigation on the Heat transfer characteristics and optimal design of the Heat exchangers of a deep borehole ground source Heat Pump system
Energy Conversion and Management, 2017Co-Authors: Zhihua Wang, Fenghao Wang, Mengjie SongAbstract:Abstract Deep borehole ground source Heat Pump (DBGSHP) is a new type of Heat Pump Heating system which extracts deep geothermal energy through Heat exchange and can be applied for space Heating in winter. To date, the development of deep borehole Heat exchangers (BHEs) is limited to the cognized structure design and there is a lack of the experimental studies. This paper presents the investigation of the Heat transfer characteristics of the Heat exchanger of a DBGSHP Heating system through both field test and numerical simulation. A field test was first carried out based on the DBGSHP implemented in a demonstration project. A numerical model was then developed to facilitate the evaluation of the Heat extraction capacity and the outlet temperature of the coaxial deep BHEs. Based on the numerical model developed, a sensitivity study was further performed to examine the effect of the primary parameters including the inlet velocity, inlet temperature, flow pattern (one was that the circulating fluid flowed from the inner pipe to the annular space and the other was that the circulating fluid flowed from the annular space to the inner pipe) and pipe diameter on the performance of deep BHE. The results from the field test indicated that the average Heat transfer capacity of each single borehole, the average COP of the Heat Pump Unit and the DBGSHP Heating system COP were 286.4 kW, 6.4 and 4.6, respectively. The simulation results matched well with the field test data, and showed that the inlet fluid velocity between 0.3 m/s and 0.7 m/s as well as the circulating fluid flowed from the annular space to the inner pipe can result in a better performance for the system of concern. The results from this study could be used as a reference basis for optimal design of coaxial deep BHE and to promote the utilization of deep geothermal energy.
-
Experimental investigation on an air source Heat Pump Unit with a three-circuit outdoor coil for its reverse cycle defrosting termination temperature
Applied Energy, 2017Co-Authors: Mengjie Song, Guangcai Gong, Zhihua WangAbstract:Abstract Air source Heat Pump Units could efficiently recover low grade waste Heat from ambient air for indoor air Heating or hot water supplying, which makes them widely applied in recent decades. For a vertically installed multi-circuit outdoor coil, a reverse cycle defrosting operation is always used to solve its frosting problem at high humidity and cold climate. Reverse cycle defrosting operation is terminated when the tube surface temperature at exit of the lowermost circuit reaching a pre-set value. It is obviously that when the pre-set temperature is higher or lower, the defrosting duration would be prolonged or more residual water left, respectively. Both of them result in potential energy waste for an air source Heat Pump Unit, or even adversely degrade the indoor thermal comfort. However, as reported, a wide range of 10–35 °C was used as the pre-set defrosting termination temperature, without a fixed value or range given. To save energy for an air source Heat Pump Unit, in this paper, an experimental methodology was firstly presented. Then, an air source Heat Pump Unit with three-circuit outdoor coil was specially selected, and experimental investigation conducted. Finally, the defrosting termination temperature was concluded suitable at 20–25 °C, around 22 °C for this study. This methodology makes contributions to the control strategy optimization and energy saving for air source Heat Pump Units.
-
numerical study on the operating performances of a novel frost free air source Heat Pump Unit using three different types of refrigerant
Applied Thermal Engineering, 2017Co-Authors: Zhihua Wang, Fenghao Wang, Mengjie SongAbstract:Abstract Air-source Heat Pump (ASHP) is a promising device using in residential buildings because of its energy-savings. Besides, R134a and R407C as environmental friendly refrigerant have advantage to apply into Heat Pump system. In this study, an investigation of a novel frost-free ASHP system, integrated with dehumidification and thermal energy storage, working with R134a and R407C as an R22 alternative, was presented. A mathematical model of the system is constructed and verified by comparison with experimental data that shows the measured results are in good accordance with the numerical ones. According to the mathematical model, the dynamic performance of the system is characterized by dehumidification and regeneration efficiency, suction and discharge pressure, COP and so on at ambient temperature of 0 °C and RH (relatively humidity) of 85%. The results show that the time for keeping the evaporator frost-free operation for R22, R407C and R134a are 29, 34 and 35 minutes, respectively. In addition, at the end of working time, the discharge pressure of compressor for R134a is 29 and 32% lower than that for R22 and R407C. What is more, at the given ambient temperature of −10 °C and RH of 85%, the average COP for R134a is 3.3 and 8.6%, respectively, which is higher than that for R22 and R407C.
-
An experimental study on the uneven refrigerant distribution over a vertically installed multi-circuit outdoor coil in an air source Heat Pump Unit during reverse cycle defrosting
Applied Thermal Engineering, 2015Co-Authors: Mengjie Song, Zhihua Wang, Ning Mao, Ying ChenAbstract:Abstract For an air source Heat Pump (ASHP) Unit with a vertically installed multi-circuit outdoor coil, many parameters would affect system defrosting performance, especially the uneven distribution of refrigerant for each circuit and downwards flowing of melted frost due to gravity from up circuit(s) to down circuit(s). Currently, the negative effects of melted frost have been demonstrated and quantitatively studied, without however giving a fundamental study on the effects of uneven refrigerant distribution due to gravity and tube internal resistance for an ASHP Unit with a vertically installed multi-circuit outdoor coil. Therefore, an experimental study on system defrosting performance when refrigerant was evenly or unevenly distributed into each circuit has been carried out and a comparative and quantitative analysis conducted using the experimental data. In this paper, the negative effects of refrigerant uneven distribution on system defrosting performance were demonstrated and an increase of 6.9% in defrosting efficiency when refrigerant evenly distributed, compared with the case of refrigerant unevenly distributed, was reported.
Zhu Yingxin - One of the best experts on this subject based on the ideXlab platform.
-
quasi dynamic energy saving judgment of electric driven seawater source Heat Pump district Heating system over boiler house district Heating system
Energy and Buildings, 2010Co-Authors: Shu Haiwen, Li Xiangli, Zhu YingxinAbstract:Abstract The electric-driven seawater source Heat Pump district Heating system is a renewable energy utilization system, but this cannot guarantee the energy-saving effect of the system. The static energy-saving judgment between this system and the conventional boiler house district Heating system was provided in a former research paper. However the static method has proved to be a very rough evaluation method and may lead to misjudgment as well. So a quasi-dynamic method, taking the total energy consumption during a whole Heating season into consideration, is established in this paper. The energy-saving index turns out to be the expression of the lower limit of the average COP of the seawater source Heat Pump Unit throughout the Heating season (COPh,mc). Then a case study is presented to show how the index of COPh,mc and the actual average COP of the Heat Pump Unit throughout the Heating season (COPh,ma) are calculated. The calculation results show that the quasi-dynamic method improves the calculation accuracy dramatically, and thus provides a better solution to the quantitative energy-saving evaluation of the electric-driven seawater source Heat Pump district Heating system.
-
Energy-Saving Potential of Seawater-Source Heat Pump District Heating System over Boiler-House District Heating System
2009 International Conference on Energy and Environment Technology, 2009Co-Authors: Shu Haiwen, Li Xiangli, Zhu YingxinAbstract:The seawater-source Heat Pump district Heating system (SSHPDHS) is a renewable energy utilization system. However, under what conditions can the system achieve its energy-saving effect and how to evaluate its energy-saving potential are not very clear in practice, yet they are of vital importance for the popularization of the system in the cold coastal area. The paper derived an expression of the critical COP value of the Heat Pump Unit for energy-saving (COPh,c) through the comparison of the SSHPDHS and the conventional boiler-house district Heating system (BHDHS) in energy consumption aspect. At the same time, the actual COP values of a Heat Pump Unit (COPh,a) under different evaporator water temperatures are calculated out by an experiment data regression model on the basis of the manufacturer's dataset. Then the comparison of COPh,c and COPh,a under several typical scenarios are presented, which make the energy-saving judgement of an SSHPDHS and its energy-saving potential readily available. It concludes that the utilization of renewable energy of the SSHPDHS cannot guarantee its energy-saving effect due to the restriction of the actual COP value of a Heat Pump Unit. It is also found that both the natural conditions of the seawater and the Heating district radius (RH) are the most important factors that affect the energy-saving potential of the SSHPDHS.
