Abstracts and Key Words

HeatSourceandColdSource

HeatingEffectofLowAmbient
TemperatureAir-sourceHeatPump
inColdAreas
WANG Weijie，YANG Li，WANG Xiaowei,
WANG Zongwei

Abstract： Combined with the actual project，the heating effect of the low ambient temperature air-source heat pump in cold areas is measured and analyzed. On the typical day of the initial heating period，the outdoor temperature range is -5 to 0 ℃，and the effluent temperature of the heat pump unit is stable，and the average effluent temperature is 41.2 ℃. On the typical day during the middle heating period，the outdoor temperature is relatively low (range of change -11.4 to -3.9 ℃)，and the effluent temperature of the heat pump unit only decreases slightly with the decrease of the outdoor temperature. The average effluent temperature is 37.1 ℃，and the overall remains stable. It complies with the article 5.4.1 ofDesignCodeforHeatingVentilationandAirConditioningofCivilBuildings(GB 50736-2012) (the water supply temperature of hot-water floor radiant heating systems should be 35 to 45 ℃ and should not be greater than 60 ℃). The heating performance coefficient of the heat pump unit in the middle heating period is lower than that in the initial heating period. In the initial heating period，the average heating performance coefficient of the heat pump unit exceeds 3.0. In the middle heating period，the average heating performance coefficient of the heat pump unit is close to 3.0. Outdoor air temperature is one of the main factors influencing the performance of low ambient temperature air-source heat pump. The performance of low ambient temperature air-source heat pump meets the heating requirements in cold areas.

Keywords: low ambient temperature air-source heat pump；heating effect；outlet water temperature；heating performance coefficient

Heat-supplyNetwork，Cooling-supply
NetworkandSubstation

HarmandPreventionofPolyurethane
CarbonizationofPrefabricated
HotWaterInsulationPipe
HE Hongwei

Abstract： The carbonization mechanism and causes of rigid polyurethane foam (hereinafter referred to as polyurethane) for prefabricated hot water insulation pipes are analyzed，and the hazards and preventive measures of polyurethane carbonization are discussed. The carbonization process of polyurethane is a thermal decomposition reaction，the main reasons are the insufficient heat resistance of foaming raw materials，the low density of polyurethane，the influent of insulation layer and the unreasonable use temperature. In order to prevent the carbonization of polyurethane，the comprehensive testing of prefabricated insulation pipes should be strengthened，the use temperature should be strictly controlled，the pipeline routing should be rationally designed，and the product quality should be improved.

Keywords: prefabricated hot water insulation pipe；rigid polyurethane foam；carbonization

RiskAssessmentofHeat-supply
NetworkLeakageBasedonFuzzy
AnalyticHierarchyProcess
HUANG Tao，YANG Di，CUI Xuyang，
LEI Wanning，BAI Chao，GAO Lin，
YANG Junhong

Abstract： Pipeline attributes，pipeline perforation，pipeline breakage and equipment failure are selected as the risk factors of heat-supply network leakage. Fuzzy analytic hierarchy process is used to determine the weights of risk factors，and the heat-supply network leakage risk assessment model based on correlation function values is established. Combined with actual cases，the leakage risk grade of a pipe section in the heat-supply network is evaluated. The actual results are consistent with the evaluation results，indicating that the fuzzy analytic hierarchy process is effective in evaluating the risk of heat-supply network leakage. The risk factor scoring has a significant impact on the assessment results. In practical application，it should be closely combined with the actual project site practice and expert opinions.

Keywords: fuzzy analytic hierarchy process；heat-supply network leakage；risk assessment；correlation function value

BuildingHeating，AirConditioning，
VentilationandThermalEnvironment

ComfortandEconomyofMulti-Line
andAir-sourceHeatPumpAir-conditioning
Systems
LIU Xu

Abstract： The difference and the cooling comfort of multi-line air-conditioning system and air-source heat pump air-conditioning system are analyzed. Combined with an engineering example，the cost and operating costs of the two air-conditioning systems are calculated. Because the multi-line air-conditioning system adopts a direct expansion end device，compared with the heat pump air-conditioning system with the end device using cold water as the heat transfer medium，the air supply temperature and moisture content of the end device are lower，but it has little effect on the thermal comfort of personnel. For the engineering example，the cost of the multi-line air-conditioning system is 343.78×104yuan，and the annual operating cost is 24.03×104yuan. The cost of the heat pump air-conditioning system is 225.28×104yuan，and the annual operating cost is 39.54×104yuan. Compared with the heat pump air-conditioning system，the differential static investment payback period of the multi-line air-conditioning system is 7.64 years.

Keywords: multi-line air-conditioning system；air-source heat pump air-conditioning system；cooling comfort；economy

PassiveEnergy-savingRetrofittingEffect
ofExistingResidentialBuildings
NI Haifeng，ZHANG Zhuofen，
ZHANG Yufeng，ZHOU Zhihua

Abstract： According to the passive energy-saving retrofitting (EnerPHit) standards proposed by the German Passive House Research Institute (PHI)，the passive energy-saving retrofitting effect of an existing residential building in Tianjin (based on the energy demand standards) is calculated and analyzed. The passive energy-saving retrofitting standard (Meeting one of the energy demand standards and building component standards that is to say that it meets the requirements for energy efficiency of passive houses) and the calculation principle of the passive house planning package (PHPP) are introduced. The retrofitting of the existing residential building involves improving the thermal insulation performance of the envelope structure，enhancing air tightness and adding fresh air unit. The retrofitting effect does not meet the energy demand standard，the heating demand and the primary energy demand meets the limit requirement，the refrigeration demand exceeds the standard；the retrofitting effect meets the building component standard. After the passive energy-saving retrofitting，the existing residential building meets the energy-saving requirements of the passive house.

Keywords: passive house；existing residential building；passive energy-saving retrofitting

MeasurementandAnalysisofHeating
EnergyConsumptioninRuralHouses
inNorthChina
YU Kecheng，TAN Yufei，LI Jianan

Abstract： In order to better understand the energy consumption characteristics of rural houses in the north China to solve the problem of high energy consumption of rural houses，three rural houses with different characteristics in Wujia Village，Yujia Town，Yushu County，Jilin Province were selected to analyze the energy consumption of rural houses through measurement and calculation. Rural house No.1 is a new type of energy-saving house. The outer wall is a 240 mm thick non-clay solid brick wall + 100 mm thick EPS styrene board and a 120 mm thick non-clay solid brick wall + plastering inside and outside. The exterior window is double-glazed. Related insulation measures have been adopted for floors，and roofs. The exterior walls and exterior windows of rural house No. 2 are the same as those of rural house No. 1，and no thermal insulation measures have been taken on roof and floor. The exterior wall of rural house No. 3 is 370 mm ordinary brick wall. The glass window is a single-layer plastic steel window，and no thermal insulation measures have been taken on roof and floor. The average indoor temperatures of rural houses No.1，No.2 and No.3 are 14.75 ℃，11.99 ℃ and 10.86 ℃，respectively，which shows that the indoor thermal environment can be effectively improved by improving the thermal insulation performance of the envelope structure. Compared with the non-insulated wall of rural house No.3，rural houses No.1 and No.2 adopt insulated walls，which can effectively reduce the heat transfer coefficient of the wall and reduce the heat loss through the exterior wall. Comparing rural houses No.1 and No.2 with rural house No.3，the converted heating energy consumption per unit area is reduced by 56.9% and 33.8%，which proves that there is a great potential for energy saving in traditional rural houses. Thermal insulation of the envelope structure can effectively reduce the energy consumption per unit area to achieve the goal of energy saving and emission reduction.

Keywords: rural house in the north China；rural house；heating energy consumption；energy consumption measurement

AnalysisandApplicationofVentilation，
PurificationandDeodorizationSystem
inLarge-scaleChemicalLaboratory
YANG Chengbin，ZHANG Shuai，
SUN Zhichao，ZHU Neng

Abstract： The laboratory pollutant composition and exhaust volume are analyzed，and the laboratory exhaust purification experiment is carried out by using the conventional ion purification equipment and developed high-energy ion purification equipment. The results show that the handling efficiency of the equipment is improved，and the treatment effect on ammonia，benzene and volatile organic compounds (VOC) is better.

Keywords: ambient air quality；laboratory exhaust；purification and deodorization；high-energy ion purification equipment

GasCombustion，GasAppliances
andGasConsumptionEquipment

EffectofCombustionProductsEvacuation
DuctFormonResistanceofCombustion
ProductsEvacuationDuctandCombustion
Performance
LYU Xinyu，LIU Wenbo，LIU Guichuan，
ZHOU Weiye，ZHANG Mengting

Abstract： The combustion products evacuation duct form of gas-fired heating and hot water combi-boilers (including the length of combustion products evacuation duct，the inner diameter of wind shielding ring and the number of elbows) affects the resistance of combustion products evacuation duct，thereby affecting the combustion performance of gas-fired heating and hot water combi-boilers. The influence of different combustion products evacuation duct forms on the resistance of combustion products evacuation duct and the combustion performance was tested through experiments. The experimental devices and methods are introduced，and the experimental data were analyzed. The experiments were performed under conditions of different lengths of combustion products evacuation ducts，different inner diameters of wind shielding rings and different numbers of 90° elbows. The parameters such as the outlet pressure of the induced draft fan，the outlet pressure of combustion products evacuation duct and the NOxvolume fraction under the corresponding working conditions were recorded. The resistance of combustion products evacuation duct，the flue gas volume flow rate，the thermal efficiency of gas-fired heating and hot water combi-boilers and the excess air coefficient were calculated. The experimental results show that there is a non-linear positive correlation between the resistance of combustion products evacuation duct and the inner diameter of wind shielding ring. The smaller the inner diameter of wind shielding ring，the faster the resistance of combustion products evacuation duct increases. For enameled combustion products evacuation duct with inner diameter of 60 mm，the resistance of a 90 ° elbow is approximately equal to the resistance of combustion products evacuation duct of 2.5 m. The thermal efficiency and NOxvolume fraction increase linearly with the increase of the combustion products evacuation duct resistance. The excess air coefficient and flue gas volume flow rate decrease linearly with the increase of the combustion products evacuation duct resistance. When the appropriate length of the exhaust pipe and the appropriate number of elbows are installed，the resistance of combustion products evacuation duct and the flue gas volume flow rate can be basically the same as that of the original air supply and combustion products evacuation ducts equipped with the wind shielding ring，and the combustion conditions are also relatively similar.

Keywords: gas-fired heating and hot water combi-boilers；combustion products evacuation duct form；resistance；flue gas volume flow rate；thermal efficiency；combustion performance

NumericalSimulationofGas-Air
Dual-stageLow-nitrogenBurner
HOU Cuicui，ZHU Yuzhou，
HAI Mingzhang，ZHANG Qingpeng

Abstract： The gas-air dual-stage low-nitrogen burner was studied and designed. The 3d numerical model of the low-nitrogen burner was established by CFD software FLUENT，and the model was verified. The simulation results were consistent with the actual situation，and the variation law of NOxgeneration could be predicted more accurately. The gas-air dual-stage structure was studied from the aspects of the gas ratio，the primary excess air coefficient and the diameter of the inner cylinder to find the combustion characteristics and NOxgeneration rules. The study found that gas grading has an important effect on temperature distribution and NOxemissions. When the primary gas ratio is 10%，the flame distribution is more dispersed，the temperature is low and the high temperature area is less，and the NOxmass fraction is lower. The effect of the secondary combustion zone on NOxgeneration is weaker than that of the primary combustion zone，and the state of the primary combustion zone is the main influencing factor of NOxgeneration in the burner. The primary excess air coefficient should be in the range of 0.7 to 1.45. Considering the combustion stability，the primary excess air coefficient should be smaller. The diameter of the inner cylinder is appropriately increased，which can achieve the improvement of the primary combustion state and the purpose of reducing NOx.

Keywords: low-nitrogen burner；gas-air dual-stage；primary excess air coefficient；gas ratio

GasTransmission，Distribution，
StorageandTransportation

InfluenceofFoundationPitEngineering
onAdjacentNaturalGasPipelineand
PipelineProtection
ZHU Qinjun，PANG Zhihui，HE Wei，
ZHAI Tianping，LI Chao

Abstract： The harmful factors of the foundation pit engineering to the adjacent natural gas pipeline and the protection measures of the natural gas pipeline are analyzed. Combined with engineering cases，the measures to protect natural gas pipelines in foundation pit engineering are discussed. The monitoring alarm value of the underground pipeline around the foundation pit is given. The special software for foundation pit supporting structure was used to calculate the ground settlement around the foundation pit，the maximum settlement of the soil was 53.9 mm，which did not meet the requirements of the code for the surrounding flexible pipelines. Two kinds of protection measures are proposed: strengthening the foundation pit enclosure strength and soil reinforcement. The large-scale geotechnical finite element analysis software Midas/GTS was used for model calculation to analyze the influence of foundation pit excavation on the natural gas pipeline and the influence of the reinforcement of the soil by sleeve valve tube grouting on the natural gas pipeline. The maximum deformation displacement of the gas pipeline was 41.38 mm，which exceeded the requirements of the code for the deformation displacement of the surrounding flexible pipeline. After the reinforcement of the soil，the deformation displacement of the pipeline decreased significantly，meeting the requirements for the surrounding flexible pipelines. After the technical and economic comparison of the engineering design scheme，the measures to strengthen the foundation pit enclosure strength combined with pipeline monitoring during the construction process were taken. The soil reinforcement scheme was used as an emergency scheme for pipeline deformation displacement exceeding the monitoring and early warning value. The provincial natural gas pipeline was monitored during the construction of the foundation pit，which shows that the protective measures taken are effective and reliable，and the operation state of the natural gas pipeline is safe and controllable during the construction of the foundation pit. At the end of the paper,the demonstration video of the foundation pit engineering is included,which can be watched by scanning the QR code.

Keywords: foundation pit engineering；natural gas pipeline；foundation pit enclosure；soil reinforcement

SimilaritiesandDifferencesof
WetHydrogenSulfideStressCorrosion
ConditionsinDomesticandForeign
DesignStandards
QIAN Xiaojuan，XIA Lin，FANG Zhenzhong

Abstract： Wet hydrogen sulfide stress corrosion is a common type of corrosion in natural gas transportation. The definition of wet hydrogen sulfide stress corrosion conditions is introduced. The similarities and differences in the requirements for selection of wet hydrogen sulfide stress corrosion materials in domestic and foreign standards systems are analyzed. By comparing the calculation formulas of pipe wall thickness，the differences between the two are analyzed.

Keywords: wet hydrogen sulfide stress corrosion；natural gas pipeline；material selection；design standards

EvaluationCriterionandApplicability
ofResidualStrengthofNatural
GasPipeline
TU Yaming，ZHAO Yuluo，
ZHANG Xiaojing，CHAI Jin

Abstract： The development of the integrity management of natural gas pipelines and the evaluation criteria of residual strength are described. The domestic and foreign evaluation criteria and methods of pipeline residual strength are summarized. The main international evaluation criteria of pipeline residual strength are elaborated，and the applicability of different criteria is analyzed. The NG-18 criterion and ASME B31G criterion are suitable for evaluating low-grade steel pipelines. The PCORRC criterion and DNV RP-F101 criterion are more suitable for high-grade steel pipelines. It is suggested that the finite element simulation combined with test should be used to evaluate the mechanical properties of ultra-high steel pipeline.

Keywords: natural gas pipeline；evaluation of residual strength；evaluation criteria；defective pipeline

DeterminationofConnectionStatebetween
BuriedGasPipelineandSteelCasing
WU Cong，CHEN Zhiguang，QIN Chaokui，WU Yibin

Abstract： The determination of the connection status between steel casing and gas pipeline in the crossing section is studied. The determination method is summarized by investigating the domestic and foreign standards. Combined with a site in Shanghai，the recommended methods in foreign standards were tested and verified. The presence or absence of electrolyte in the casing space can be determined by installing a water level monitoring device. Whether metal contact occurs between the casing and the inner pipe can be judged by the potential test，internal resistance test and casing depolarization test. When the potential difference test result is greater than 100 mV，the internal resistance test result is greater than 0.01 Ω，or the inner pipe-reference electrode potential does not have a positive deviation of the same amplitude as the casing-reference electrode，it can be considered that there is no metal contact between the casing and the inner pipe. On the contrary，if it is determined that there is metal contact，4-wire IR drop test can be performed to determine the contact position，thereby accurately analyzing the connection state between the casing and the inner pipe.

Keywords: casing；gas pipeline；short circuit；connection state

ComparisonofGasPipelineCorrosionRisk
BasedonGreyTargetDecisionModel
ZHANG Xuejiao，MA Xuqing，
GUO Baoling，ZHANG Yuxing

Abstract： The buried steel gas pipeline is taken as the research object to form a scheme set. The soil resistivity，pH value of the pipeline ambient environment，pipe-to-ground potential，content of sulfate reducing bacteria，pipeline operating pressure，buried depth of pipeline and service time are selected as the parameters affecting the pipeline corrosion to compose the parameter set. The grey target model effect sample decision matrix is established，and the decision matrix is obtained by initializing with the operator of "rewarding the good and punishing the bad". The entropy method is used to calculate the weight of the pipeline corrosion parameters，which does not involve the subjective judgment of the decision maker. The calculation results are accurate and objective. The positive and negative target centers of the gray target model are obtained from the decision matrix，and the comprehensive target center distance of each pipeline parameter set is calculated. The corrosion risks of different gas pipelines are compared by the comprehensive target center distance. The comparison results are consistent with the field test results，indicating that the multi-parameter gray target decision model based on the entropy method to determine the weight can be applied to the comparison of pipeline corrosion risks under the influence of multi-parameters.

Keywords: gas pipeline；corrosion risk；operator of "rewarding the good and punishing the bad"；entropy method；grey target decision model

LiquefiedNaturalGas

ApplicationofLNGMembrane
StorageTanksinAsia
CHANG Xuning

Abstract： The application of LNG membrane storage tanks in LNG terminals in Asia is investigated，and the application of the membrane patent technologies including France GTT，Japan IHI，KHI，MHI and South Korea KOGAS in Asia is introduced. Five kinds of patent technologies are compared. The application effect and development of membrane storage tanks are analyzed，and the future application is prospected.

Keywords: LNG membrane storage tank；Asia；membrane patent technology

BuildingGasSupply

DeepeningDesignofIndoorGas
PipinginPrefabricatedHousing
WANG Xia，JING Shuai，JIA Shize

Abstract： In order to make the installation of indoor?mechanical?and?electrical?equipment and piping be carried out synchronously with the construction of the main project，the gas specialty needs to intervene in the design stage of housing scheme，and cooperate with the professional deepening design of indoor gas piping and equipment. Based on the construction requirements and characteristics of prefabricated housing，the general requirements for the professional deepening design of indoor gas piping and equipment，the requirements for reserved holes of gas piping are proposed. The requirements and specific practices of four ways of indoor gas piping buried in walls and ground are given. Other matters needing attention in professional deepening design of indoor gas piping and equipment are pointed out.

Keywords: prefabricated housing；indoor gas piping and equipment；deepening design；reserved hole；buried installation

GasEquipmentandMaterials

WaysofImplementingLadderGas
PriceBillingforIoTSmartGasMeters
SHAO Zehua

Abstract： The structure and function of the IoT smart gas meter based on the ladder gas price billing are introduced. Combined with the ladder gas price scheme and the billing principle，the measures to ensure the implementation of the ladder gas price (clock synchronization，calculation of the implementation time of ladder gas price cycle and gas price determination) are analyzed.

Keywords: IoT smart gas meter；ladder gas price；billing

CalibrationMethodofDiaphragmGas
MeterBasedonWeighted
AverageRelativeError
QUAN Yaqiang，TANG Yongqiang，
LIANG Yongzeng

Abstract： Based on the study of the range ratio of the diaphragm gas meter，the curve opening degree of the relative error curve，and the weighted average relative errorEWME，according to the requirements of the domestic and foreign standards for the relative error curve of the diaphragm gas meter and theEWME，the related characteristics and data of the developed wide-range diaphragm gas meter are interpreted. The simplified calculation formula of the weighted average relative errorEWMEof the diaphragm gas meter is derived，and the calibration process target of diaphragm gas meter is determined based on the rule thatEWMEtends to zero. According to the calibration process target and the characteristics that the curve opening degree of the relative error curve does not change with the translation of the relative error curve found by the long-term experimental research，the calculation formula of the adjustment of curve displacement is derived，and 2 equivalent calibration process schemes are determined. The calibration process is given and verified by an example. The results show that the relative error curve of the diaphragm gas meter calibrated by this method is more reasonably distributed near the zero line. The relative error and the curve opening degree of the relative error curve not only meets the requirements of enterprise internal control index，but also meets the requirements ofDiaphragmGasMeters(GB/T 6968-2019). The weighted average relative errorEWMEis 0.19%，which complies with the requirement thatEWMEshould be within ± 0.6% in OIML R137-1 & 2: 2012 "GasMeters".

Keywords: diaphragm gas meter；range ratio；relative error curve；calibration；weighted average relative error

GasInformatization

ApplicationofGasIoTSecurityChip
toStrengthenInformationSecurity
JIN Jieyu

Abstract： Taking a gas IoT project as an example，the safety chip of home narrowband IoT intelligent gas meter cooperates with the IoT safety management platform and plays a key role in strengthening information security in the intelligent gas metering. The typical IoT architecture，challenges faced by IoT information security，architecture and application process of IoT security management platform，features，basic functions，key management mechanism，and information security advantages of security chip are analyzed. The key application steps such as security chip design，authentication detection，security release as well as the application effect of security chip are introduced. Practice shows that the security chip can support the whole process information security solution from intelligent gas meter to gas billing management system，and provide a strong guarantee for the construction of the urban gas IoT security system.

Keywords: gas IoT；intelligent gas meter；security chip；information security；security platform；key management