Introduction

Energy-storage air conditioning system, usually classified as ice storage and chilled water storage, is this kind of air conditioning systems adopting electrically driven chiller which produce and store cooling capacity in the form of ice or chilled water at the period of low utility rate like the nighttime, and release the cooling in the daytime when the utility rate is higher.

Energy storage technology is a critical technical measure to shift electricity consumption at peak time to the valley time, optimize resource utilization and protect the environment. The ice (chilled water) storage, as a proven technology has found wide application in China and demonstrated its effectiveness and bright future as shown below:

• Shift electricity consumption at peak time to valley time as well as balance power supply;
• Minimize air pollutant emission from power plants and emission of CFC and combustion products from buildings;
• Improve generating efficiency of power plants and energy utilization rate thereof;
• Reduce the gross electrical load and electrical needs to release the burden and urge for construction of new power plants (generator);
• Cut down operation cost of air conditioning system for customers.

Operation rationale of energy storage system

• Meet the needs at peak load: released cooling shall allow for peak load in the afternoon
• Save operation cost: cooling shall be released during peak electricity rate time in the condition of designed daytime load balance.
• Make full use of electricity at valley time: stored cooling should be fully released at the design day

Control mechanism of UPPC^® energy storage system---Globally supervisory optimization ensures the energy storage air conditioning system operating at the minimum overall energy use

In adherence to the operation principle of energy storage, UPPC coordinates the operation of chiller, ice storage, plate heat exchanger, system circulation pump, cooling tower, and control valve and adjusts the control strategy real time in case of different running condition to ultimately achieve the optimal system energy efficiency.

Algorithm of real-time best path self-seeking of UPPC^® control system

• Tailor-made operation optimization for dual-duty chiller
• Tailor-made volume optimization for ice tank
• Tailor-made system variable flow control
• High-efficiency real-time global supervisory optimization algorithm for the optimal energy efficiency of chiller plant
• Real-time response to load and weather change to realize real-time load prediction
• High-performance transmitters with high response speed based on PLC precision control