THERMAL STORAGE MAXIMUM DEMAND MANAGEMENT

Thermal assumes Storage cooling effect in the latent heat of the ice banks (Fig. 8.1) or eutectic salt (that undergo phase changes), and use it when necessary. Ice banks are used in dairy factories for the past many years to overcome their peak cooling load. The same concept can be used to reduce energy costs for operation of the refrigeration machine during off-peak hours storage cold for use during peak hours. This reduces the number of refrigerating machines that might need to meet peak load cooling. Energy savings accumulated by reducing the registered maximum kVA Demand and Peak-time energy payments (if applicable); quantum depend on the load profile of the plant.

In conventional ice of the Bank consisted of sheet steel in coils in a tank filled with liquid ammonia. Peak ice was built on the coils up to 2 thickness. Excitation of chilled water around the ice was preserved for better heat transfer to the process.

Modern Ice banking System is modular, insulation, polyethylene tank containing spiral plastic tube heat exchanger is surrounded by water. The tank is available in many sizes ranging from 45 to over 500 tons of hours. The night of 25% ethylene glycol, and is cooled by the chiller and circulated through the heat exchanger, heat recovery, until, finally, about 95% of the water in the tank, frozen. Ice is built uniformly throughout the tank patented temperature averaging effect of closely spaced counterflow heat exchanger pipes (Fig. 4.1). The water is surrounded by ice by freezing process and can move freely as the ice forms, preventing damage to the tank. At night, water-glycol is circulated through the cooler and tank's heat exchanger, without going through the process or unit. Fluid around -3C to -4 C and freezes water around the heat exchanger. The next day, the stored ice cools a solution of 1C to 11C. temperature modulailng valve is installed in 6C in a bypass loop around the tank allows sufficient number 11C of the liquid to get around the tank, with a mix of 1C F fluid, and to achieve the desired 6C temperature. 6C fluid enters the condenser, where it cools the air, as a rule, from 24C to 133C. Liquid leaves the coil on 16C, there is a cooling and cooled to 11 C.

It should be noted that, in making ice at night, hmm must cool the water-glycol -3Cto -4C, not to produce 6C water temperature required for conventional air-conditioning systems. This has the effect of "de-rating, rated chiller capacity by about 30 to 35 percent. Efficiency of the compressor, however, will vary only slightly (better or worse), as lower night temperatures result in cooler condenser temperatures and help keep the unit running efficiently.

Temperature-regulating valve in the bypass loop has the added advantage of providing unlimited capacity management. At moderate temperatures for many days, in spring and autumn, the chiller will be capable of providing all necessary for cooling a building without using the stored cooling. When buildings actual cooling load is equal to or less than hmm' s ability, all of coolant through a bypass circuit. Ethylene glycol industrial fluid that is specially designed for low viscosity and superior heat transfer characteristics. They contain multi-component corrosion inhibitor system, which allows the use of standard system pumps, seals and air handling coils. Due to small differences in heat transfer coefficient between the water-glycol and plain water, liquid temperature can be lowered by one or two degrees. This is easily achieved by the ice.

Recently, salt hydrate, which can change from solid to liquid at a temperature of -33 to +27C. salt hydrates are HDPE nodules; the number of these nodules are enclosed in a tank through which the chilled water or in brine can be skipped. Some hotels and industries are already using this technology.

Energy consumption generally increase with thermal storage, however, it becomes compensated by the energy tariff exemptions and reduction of the maximum demand charges...