Control Of Thermocline In A Temperature Stratified Chilled Water Storage Tank

The air condition system with chilled water storage is developing as the time goes.It gets powerful competitiveness not only in the aspect of the potential capability balancing the peak and valley load difference but also in the field of economic.Also,when the energy supply of emerging technology industry is getting more,facilities of chilled water storage can be used as a backup cooling source,taking the hidden danger of accidental blackout away.In this paper,the investigation of the inherent law on thermocline in a chilled water storage tank and the influence on availability of volume among various operation strategies is in an approach which is closer to practical engineering.What is expected to investigate in the paper is not only the more advantageous availability of a chilled water storage tank in a ideal condition,but also a more comprehensive evaluation of the availability of the water tank with the various operation modes.By the calculation of numerical simulation,the target is the influence on the performance of storage tank,which is caused by height-to-diameter rate in the scale of practical engineering projects,the permitted water temperature of the chiller at the end of charging process common in the market,flow rate and repeated charging operation.Based on the factors above,the influence of thermocline and economy of different operation modes of the air condition system with chilled water storage is to be done.Based on the size of a chilled water storage tank,permitted water temperature of a water chiller and the setting of flow rate in a practical engineering project,a physical model of a temperature stratified chilled water storage tank is set.The numerical simulation of the process of charging and discharging as well as the model verification based on practical operation data is carried out.The numerical simulation calculation shows the influence of height-to-diameter rate in the scale of 0.53 to 1.8.The performance of chilled water storage tank is getting better with the increase of height-to-diameter rate.When it comes to the temperature,we jump to the conclusion that the performance of chilled water storage tank is better when the permitted water temperature is close to that of upflow.Lower flow rate in the reasonable range improves the capability of the chilled water storage tank.While repeated charging process reduces the capability of the chilled water storage tank in the following process.The thermocline is thinner when we make full use of the low electrovalence time at night to charge chilled water at a low and constant speed.When it comes to the city which has big electrovalence difference,it can save more operating expense to use all the chilled water in the high electrovalence time.While it gets thinnerthermocline and more economic benefits to discharge chilled water at a low and constant speed in the city whose high electrovalence is constant value.