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Procedia Engineering 205 (2017) 1173–1178
10th International Symposium on Heating, Ventilation and Air Conditioning, ISHVAC2017, 1922 October 2017, Jinan, China
The Measured Analysis of Heating Performance of The Sewage Source Heat Pump System of a University in North China Huixing Li1, *, Yunlong Yang1, Hao Sun1, andGuohui Feng 11
Department of Municipal and Environment Engineering, Shenyang Jianzhu University, Shenyang, China 110168
Abstract The energy crisis and environmental pollution has become a major problem facing the people. As a green energy-saving technology, the sewage source heat pump system not only makes full use of the rich water resources, but also conducive to environmental protection. In this passage, we take an sewage source heat pump system of a university as the research object, test the Sewage temperature, supplying and returning water temperature of heat pump unit and the Indoor hot and humid environment indoor, in the measure of the use of ultrasonic flowmeter, temperature recorder and power quality analyser. Analyze the cop value of sewage source heat pump system, determine the operating characteristics of sewage source heat pump system, analyze the effect of the sewage source heat pump system so that we can make full use of the sewage source heat pump technology is better used in other buildings. © 2017 The Authors. Published by Elsevier Ltd. © 2017 The Authors. Published by Ltd. committee of the 10th International Symposium on Heating, Ventilation and Air Peer-review under responsibility of Elsevier the scientific Peer-review under responsibility of the scientific committee of the 10th International Symposium on Heating, Ventilation and Conditioning. Air Conditioning. Keywords: Air conditioning system Microbial contamination Influencing factors of microbial concentration
1.Introduction With the increasing proportion of building energy consumption in total energy consumption, more and more attention has been paid to the reduction of energy consumption and the development of new energy sources.Sewage source heat pump with its energy saving, environmental protection, renewable and other advantages show strong potential for development. At present,The energy efficiency of the sewage source heat pump in Japan is close to the existing conventional water source heat pump. Reed, Stockholm, 40% of buildings using heat pump heating, of which the use of sewage treatment plant 10% as a water source. Now, the coal-fired power plant, coal-fired heat * Corresponding author. Tel.: 189-4024-2868;. E-mail address:
[email protected] 1877-7058 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 10th International Symposium on Heating, Ventilation and Air Conditioning.
1877-7058 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 10th International Symposium on Heating, Ventilation and Air Conditioning. 10.1016/j.proeng.2017.10.187
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plant is the main source of heat in Liaoning city of Shenyang Province, and clean energy, the proportion was only 12.8%, which is the main form of application of ground source heat pump, the gas, electricity and solar energy. Shenyang city center of the existing clean energy heating area of 3100x104m2, of which ground source heat pump, sewage source heat pump accounted for the largest, which plays a good role in improving the air pollution in winter in Shenyang. (Government of Shenyang 2014)In this paper, field investigation and test on a University of Shenyang city sewage source heat pump system, through calculation and analysis of the sewage source heat pump system COP value, determine the operating characteristics of the sewage source heat pump system, the evaluation system of the indoor thermal comfort, and summarizes the problems in the operation of the problem, provide a theoretical basis and application basis for Shenyang in the future development of the sewage source heat pump[1].
Project overview The college is located in Dadong District, Shenyang City, the total construction area of 326,200 square meters,the use of indirect primary sewage source heat pump system heating, mainly used in teaching areas, the application area of 35,000 m2, sewage sources for the nearby factories of industrial wastewater and campus life Sewage. The system uses 4 sets of sewage source heat pump units, dual-use two[2]. Each unit is equipped with 2 compressors. Heat source side of the circulating pump for the five vertical single-stage centrifugal pump;The user side of a circulating pump and the secondary circulation pump are three vertical single-stage centrifugal pump; water pump 2, automatic replenishment. The shape of the sewage pool is , the sewage through the sewage tank plate heat exchanger and circulating water heat exchange, sewage tank with sewage pump regular blowdown, about 3 months sewage. The main equipment parameters are shown in Table 1 and table 2.(Xu Meng et 2009) Table1 Parameters of sewage source heat pump Model
Heating capacity
Power rating(hot)
Refrigerating capacity
Power rating（cold）
WCFXP54TGDN
1838KW
336KW
1573KW
253KW
Table2 Parameters of water pump Water pump
Model
Flow(m3/h)
Lift(m)
Rotate speed (r/min)
Heat source circulating pump
KQL200/250-45/4（T）
380
24
1480
A circulating pump on the user side
KQL200/270-18.5/4（T）
300
13
1480
User side secondary circulation pump
KQL250/250-45/4（T）
600
17
1480
2.Methods 2.1.Testing instruments and testing contents The main contents of the test include indoor temperature, water temperature and flow rate of the inlet and outlet of the sewage, the water temperature of the evaporator, the water temperature and the flow rate of the circulating water in and out of the condenser. The main instruments of this test are temperature and humidity from the instrument, ultrasonic flowmeter and energy meter, the instrument parameters in Table 3, Table 4. Table3 Temperature and humidity recorder parameters Name and model
Range
Intensive reading
Resolution
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RR002
-10～50℃
±0.5℃
0.1℃
TR001
-30℃～125℃
±0.5℃
0.1℃
Table4 Ultrasonic flow meter parameter Name and model
Applicable pipe diameter ϕ
Measured fluid temperature
Velocity measurement range
FSCS10C1-00C
13mm～6000mm
-40℃～200℃
0～±32m/s
2.2. Operating mechanism The operating mechanism of the original sewage source heat pump is to transfer the heat or cold quantity in the sewage to the building. This process can be summed up in three phases: Medium and sewage heat transfer in the evaporator, the heat absorption water evaporation, this is the first stage; After absorbing heat, the medium is sucked into the compressor to form a high temperature and high pressure gas. At this time, the gas enters the condenser and the heat is brought into the condenser, which is the second stage;The high temperature and high pressure gas medium in the condenser releases heat, and heat exchange with the water in the end system, and then the temperature of the water is released to each room of the end of the system to complete the heating, which is the third stage[3]. The original sewage source heat pump system uses the energy contained in the sewage to replace the traditional cold and heat source for heating and cooling. This process uses only a small amount of electrical energy. Sewage is a renewable energy, but also a green energy, and its temperature is affected by the environmental temperature is small, so that the system is stable, both green and energy-saving and efficient.
3.Results This test a total of 30 days of uninterrupted.During the test, the sewage flow rate was 193m3/h, the intermediary circulating water flow was 247m3/h, and the end user's circulating water flow rate was 254m3/h.
3.1.The indoor test results The test selected a total of 4 typical air-conditioned rooms, of which two rooms of indoor heating guarantee rate of 100%, a room of 62%, another room is 0%.Specific temperature test results in Table 5. Table5 Typical room temperature test results Room number
testing time
1 2 3 4
January 21st 10:00～February 20th 10:00
Measured room temperature(oC)
Design temperature(oC)
Indoor heating rate
18.5～21.8
100%
16.5～17.0
0 ≥18
17.5～18.5
62%
21.3～30.6
100%
3.2. Analysis of Performance Test Results of Heat Pump Unit FIG.1 shows the change of inlet and outlet temperature of the system,Water temperature in the range 12 ℃ ~
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15 ℃, water temperature drop of about 3 ℃ ~ 6 ℃.In this system, the sewage temperature is stable, as the heat source is ideal.
Figure 1. Inlet and outlet temperature of sewage
The instantaneous heat absorption and heat release of the heat pump unit determine its performance.The heat absorption and heat and evaporator and condenser inlet and outlet temperature is directly related.The temperature changes shown in FIG.2.The average temperature of the inlet and outlet of the evaporator is about 12.3℃ and 9.4℃ respectively,the temperature difference is about 3 ℃.The average temperature of the inlet and outlet of the condenser is about 41.9 ℃ and about 46.3℃, and the temperature difference is about 4.4 ℃.
Figure 2. Inlet and outlet temperature of evaporator and condenser
Instantaneous by formula (2), (3) calculate the heat absorption heat pump unit derived and the supply of heat.The instantaneous power consumption of the compressor can be measured by the energy meter.FIG.3 for its changes.The instantaneous power consumption of the compressor substantially stable.The average value of 276kW, the unit instantaneous heat absorption and heat changes are within the normal range, the average were 837 kW and 1280kW.
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Figure 3. Instantaneous heat absorption, heat supply and compressor instantaneous power consumption of heat pump unit
By the formula (4) derived calculate the heating coefficient of performance of heat pump.During the test, its variation curve over time is shown in Fig.4.As can be seen from the figure, the instantaneous COP value of the heat pump unit is relatively stable.The lowest value is 3.73, the highest value is 5.29, the average is 4.64.Consider the other equipment in the system power consumption, energy consumption ratio of 3.9 or so,showing its stable performance, high energy efficiency.
Figure 4. COP value of heat pump unit
The calculated heat transfer coefficient K of the sewage heat exchanger is 66W/ (m2·℃).This is due to the poor quality of the original sewage water, easy to form dirt on the wall of the heat exchanger, reducing the heat transfer coefficient of the heat exchanger, the effect is affected. 4.Equations
qw = 1 / 3 × 600QwcwVw (t w,i − t w,o )
（1）
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where qw is the sewage instantaneous heat rele+ase, Qw is the average density of sewage in sewerage, Vw is the Sewage flow, Cw is the average specific heat capacity of sewage, and tw,i,tw,o is the inlet and outlet temperature of sewage.
q e = 1 / 3 × 600 Q e c eV e ( t e .i − t e .o )
（2）
qe is the unit evaporator instantaneous heat absorption, kw; Qw is the average density of intermediate water, c V kg/m3; e is the medium level specific heat capacity, e is the intermediary circulating water flow, m3 / h;
where
t w.i , t w.o is the inlet and outlet temperature of evaporator, ℃ q c = 1 / 3 × 600 Q c C cV c ( t c .i − t c .o )
（3）
qc is the unit condenser instantaneous heat supply, kw; Qc is the average density of user side circulating c v water, kg/m3; c is the user side circulating water level than the heat capacity; c is the user side circulating water
where
flow, m3 / h;
t c ,i , t c , o
is the inlet and outlet temperature of evaporator, ℃[4]
5.Discussion and Conclusions Through the test that heat pump as a heat source, the sewage water temperature fluctuations, adequate water,is the ideal.The original sewage source heat pump system has stable performance and high energy efficiency,to meet the needs. While because of poor quality of primary sewage, affect the heat transfer efficiency of sewage heat exchanger and easy to corrosion, plug the pipeline.Therefore, to a wide range of use and promotion of primary sewage source heat pump system, we must first solve this problem. Although there are still some problems in preventing clogging and anti-corrosion,efficient, stable, energy saving, environmental protection will make it a wide range of advantages, become one of the mainstream way of future heating. Acknowledgements First of all, sincere thanks to my tutor Huixing Li. She squeezed out the time in the busy teaching work to review and modify my paper. Secondly, thanks for the help of my class-mates, friends, thank them for my proposed suggestions and comments, with their support, encouragement and help, I can successfully complete this article. References [1] Circular of the General Office of the People 's Government of Shenyang Municipality on Printing and Distributing the Urban Heating Plan of Shenyang City (2013 ~ 2020) [EB / OL]. (2014-09-09). Http: // www. Shenyang.gov.cn/zwgk/system/2014/11/10/010100660.shtml. [2] C tao Shen, D gen Peng,S Hu,A liang He . Nanchang sewage source heat pump system engineering examples and application feasibility analysis [J]. Renewable Energy, 2014,32 (10): 1510-1514. [3] M Xu ,Y Xu, D Sun. Key technology and engineering practice of primary sewage source heat pump [J]. Energy Conservation Technology, 2009,27 (1): 74-77.4 Z yi Zhuang ,Y Xu ,X Li ,D xing Sun . Test and analysis of winter operating conditions for sewage source heat pump units [J]. HVAC, 2008,38 (11): 133-136. [4] Y Yao, Y N Song. Research of system performance of sewage-source heat pump with fouling effect [J].J Harbin Inst Technol 39(4) (2009) 99~603
