| With country’s vigorous support on industry, the development of the industry hasbeen prosperous so far. Industrial construction increases year by year and airconditioning system is becoming more and more widely used in industrial workshop.However, due to the characteristics and technological requirements of industrialbuilding itself, cooling time of air conditioning system takes up large proportion of theyear, some even for the whole year, and the air conditioning system energy consumptionis huge. The vast majority of existing factory buildings’ air conditioning system adoptschiller and cooling system throughout the year. Chongqing is surrounded by two riverswith rich water resources, which brings about advantages in the surface water sourceheat pump system, especially for industrial workshop. At the same time, cooling timefor industrial building is longer than usual units and river water would be cooler in earlysummer and late summer. To make full use of water resources, it is considered to useriver water to be delivered directly into the end of the unit instead of being delivered toheat pump units cooling, thus reduce the energy consumption of the air conditioningsystem running for the whole year.Existing study on surface water source heat pump lacks of theory for systemenergy consumption and operation regulation. Because of restriction of factors such astime and space, the existing study of the surface water source heat pump ignores thewater temperature changes and considering the source water temperature as a fixedvalue while actual water temperature is changing all the time. And on the other hand thetemperature changes are very important for the analysis on the system energy savingeffect. This study is based on surface water source heat pump system of an industrialbuilding in Chongqing, with comprehensive consideration of system part loadcharacteristics and optimization strategy for the water temperature changecharacteristics, providing theoretical basis for high efficient and economic operation ofthe system and a reference for engineering application.First, analysis on characteristics of industrial buildings was made; then theirworking load characters were studied too. Use DeST-c energy consumption simulationsoftware to simulate the dynamic load of the workshop and divide partition loadaccording to the control demand. Using the whole life cycle cost (LCC) calculationmethod with the consideration on dynamic load characteristics, dynamic water temperature and variable frequency of inlet water pump aiming at the best way to getwater, the final LCC value was compared with the conventional system. The LCC valueof surface water source heat pump is32.863million yuan while LCC value of normalsystem is38.948million yuan, the surface water source heat pump system shows theadvantages of energy saving.Then carry out analysis on the composition of the surface water source heat pumpsystem LCC value, to get the main factors influencing the LCC value is its operationcost within the period for running. After analysis on the composition and characteristicsof energy consumption, the result shows its main part is operation cost within operationlife where heat pump units, water pump, circulating pump, chilled water pump accountsfor the proportions of79.3%,5.8%,5.3%,9.6%respectively in the whole system energyconsumption, and energy consumption of heat pump units and frozen water pump isgreater. The following three kinds of optimization plan are put forward according toabove factors:①Optimization of river water straightly supply in the early and late summerConsider river water to be supplied directly into the end unit to reduce theoperation time of main working unit and the energy consumption of air conditioning.1）For the determination of early and late summer, the design for straight supplysystem refers to the over ground pump house unit, relative humidity is up to75%,moisture content is up to17.9g/kg, indoor parameters remains steady. Then carry outcontrast of outdoor air humidity ratio and moisture content to determine the straightsupply period (April1stto May24th, and September18thto October31th).2）According to comparative analysis on energy efficiency contrast betweenventilation cooling mode and water cooling mode in straight supply period, whendifferences between temperature outdoor and designed indoor reaches-17.0℃≤t≤-1.2℃, and cooling load≤335.3kW, ventilation cooling shows more energyefficiency effects than water cooling method. It is obtained by calculation analysis thatLCC value of this auxiliary cooling method is27.222million yuan, which is less thanLCC value of32.863million yuan of the surface water source heat pump system. So theuse of auxiliary optimization of direct supply has large energy saving potential②Load distribution optimization of heat pump units under partial loadThe load simulation result shows that, system load remains under50%for morethan84.8%of the time during cooling season, so optimization the heat pump unitsunder partial load operation characteristic optimization was carried out. On the condition that constant temperature differences of water by the load side and the sourcewater side stayed at5℃, it is concluded that when a single heat pump unit load rate ofPLR is in the60%to90%, its EER is higher, when at80%its EER reached themaximum value. The scheme of the4sets of heat pump unit work in parallel when theyevenly share the load shows a better energy-saving advantage. And by subsectionadjustment methods, that is when PLR <28%,2sets of uniform share the load; whenPLR>28%, four units share the load, the energy saving effect is better, LCC is obtainedat26.031million yuan by calculation.③Frequency conversion operation of frozen water pumpThrough the adoption of frozen water pump frequency conversion control, frozenwater pump operation cost is169,400yuan each year, saving34,800yuan comparedwith the fixed frequency operation. Using segmented regulation and direct supplyauxiliary optimization at the same time, LCC value is25.836million yuan, showingcertain advantages of frequency inverter control on freezing water pump in energysaving.Finally, SPSS software was used to get dynamic EER SOEER which fits thedynamic temperature and the dynamic load of the system. After inputting dynamic load,dynamic river water temperature and meteorological parameters of typical year into themodel, EER per hour reaches17.69under direct supply period and4.25under heatpump period. And after inputting the observed meteorological parameters of2012intothe model, the average EER reaches17.91for direct supply period and4.26under heatpump period, which is quite similar to conditions in typical year. It is acceptable to carryout system operating efficiency analysis under typical meteorological parameters, andcorresponding optimization scheme is reliability.Study in this paper shows advantages of direct auxiliary optimization in earlysummer and late summer for energy saving, at the same time taking dynamictemperature and dynamic load into the generation of system control plan, makingcertain guiding significance on the engineering application in the future. |
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