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The use of a high-efficiency solution heat exchanger and a high-efficiency high temperature generator has brought about a 12% (EXA series) and 7% (EX series) or more saving of energy with gas [compared with the conventional models].
The use of Hitachi's unique ACA flow for the cooling water system allows for a large temperature differential (chilled water, cooling water) with the standard frames. A large temperature differential reduces the follow rates of the water systems (to 69% for the chilled water system and 81% for the cooling water system), thereby reducing the water pump power consumption and the air conditioner air flow rate. This in turn reduces the power consumption of the total air conditioning system.
In the parallel flow system, the diluted solution coming out of the absorber is divided into two flows. These two flows of solution are sent to the high- and low-temperature generators separately. The system holds the flow pressure of the high-temperature generator lower than the series flow (indicated by "(1)" in the figure), while keeping an enough margin for crystallization in a low-temperature condition (indicated by "(2)" in the figure). In addition, the performance of absorption cycle is increased because the rate of solution flow into the high-temperature generator is made lower than that of series flow.
Automatic control, one-touch operation, and good compatibility with the other equipment make operations easy.
Advanced technology prevents trips caused by a high-temperature condition of the cooling water.
Each model is less than 1,900mm in height (without outer easing), facilitating it to becarried in the machine room.
The chilled/hot water piping, cooling water piping, and fuel piping are all provided at the back of the chiller unit. For the 141 to 352kW models, all the pipes are at the same height. All this facilitates piping design and connection when multiple chiller units are installed.
The combination of PID control by detection of chilled/hot water outlet temperature, three position control of combustion rate and RS proportional control has significantly improved the outlet temperature stability and the response to load fluctuation.
The air-fuel ratio is kept constant to assure stable and efficient combustion.
The new intelligent control of multiple chiller heaters that is equiped with efficient control capabilities based on a simple load calcuration function and an outlet temperature monitor function using chilled water temperature is available for the use who wants to "obtain the desired temperature quickly" or "save energy by operating an optinum number of units according to the load." This control also monitors the operating hour of each of the units to equalize the operating hours of all the units by stopping the unit that has been operating longest, etc. It does not require any temperature sensors for the chilled/hot water common header.