Steam Double Effect Absorption Chiller-Heater

  • EX Series: 120 TR to 5600 TR
  • Steam Consumption Rate 3.5 kg/hr-TR
  • EXS Series: 120 TR to 5600 TR
  • Steam Consumption Rate 3.8 kg/hr-TR
  • V Series: 120 TR to 1000 TR
  • V Series : Standard EffiSteam Consumption Rate 4.5 kg/hr-TR
Hitachi Developed Next-Gneration EX Series Absorption Chillers to Realize High Efficiency by Fully Utilizing Creativity and Advanced Technologies

Excellent Energy Saving Effect with the World’s Highest Steam Consumption Rate of 3.5kg/h・RT
High Efficiency Achieved by Hitachi’s Creativity and Advanced Technologies

Stage evaporation and absorption cycle

High efficiency was achieved by employing a 2-stage evaporation and absorption cycle. By dividing the evaporation and absorption cycle into two (upper and lower) stages and running the lower-stage evaporation and absorption cycle in the ranges of 15℃ to 11℃ chilled water temperature and 32℃ to 34.5℃ cooling water temperature, the concentration of solution can be lowered to the same as that of light light load operation. As a result, the concentration difference between generator and absorber can be increased and the flow rate of circulating absorbent in the whole cycle can be reduced. Thus we succeeded in increasing cycle efficiency by reducing the flow rate of circulating solution, which in turn cuts not only the heat radiation loss that results from the cooling water’s heat deprivation, but also the heat (flue) that is used for heating in the high-temperature generator.

High-efficiency plate heat exchanger

Low-and high-temperature solution heat exchangers are important elements that have a great influence on the efficiency of the absorption chiller. We employed plate heat exchangers of welded construction that are high in efficiency and can easily be downsized and connected in series to keep flow velocity at an optimum level even when the flow rate of circulating solution is low. Thus we succeeded in achieving high efficiency and compact size at the same time.

Drain heat exchanger

The drain heat exchanger exchanges heat between the warm refrigerant that is returned from the low-temperature generator and cool solution that comes from the absorber and thus preheats the solution that is sent to the high-temperature generator.

Chiller Operating Characteristics

Hitachi absorption chillers are distinguished not only by their energy saving effect under rated conditions but also by a high energy saving effect under partial loads. Its energy saving effect is available also in winter and intermediate seasons when cooling water temperature is low. Besides, due to the unique solution circulatint flow control developed by Hitachi, they operate stably in a whole range from high to low load conditions. The figure at left shows a sample relational curve between cooling capacity (%) and fuel consumption (%).

How to Select a Model According to Steam Supply Pressure

Standard steam supply pressure is 0.8MPa (gauge). When steam supply pressure is different from this value, cooling capacity needs to be corrected according to the figure at left for selecting a model. When steam pressure is 0.4MPa and the cooling capacity is 330 RT Required maximum capacity Q’ =(330RT × 100) / 73% -452 RT HAU-CW500EX (or V) needs to be selected. This graph is presented only for model selection. Be careful that it does not present the capacity change resulted from pressure fluctuation during operation. Energy Saving, High Reliability and Stability Are Assured even during Long-Term Operation and Optimal control of dilution operation time contributes to energy saving in the whole system Solution diluting operation time before stopping the chiller is calculated and controlled by microcomputer to optimize stop time.
As a result, the operating time of the pump and cooling tower during dilute operation can be reduced, making it possible to save energy in the whole system.

Adapted for heavy load operation (annual operating time of 4,000 hours or more) as standard

In addition to the 2-stage evaporation and absorption cycle (EX series) and ACA flow (V series), a paralell flow system is employed to realize a low-concentration cycle. Even under loads as heavy as 4,000 hours of annual cooling operation time, you can operate the system at high reliability without worry.

Safe operation assured by reinforced protective maintenance and abnormality prediction functions

Protective maintenance and abnormality prediction functions are incorporated to assure efficient and stable operation.