Press Release Back Number(2003)

Development and sale of a hybrid absorption-type refrigeration unit that uses low-temperature industrial wastewater-The world's first energy-saving unit that produces cold water using hot wastewater-

November 11, 2003

Chubu Electric Power has announced the development of the "H-ADREF," a hybrid absorption-type refrigeration unit (featuring output of 70 kW), under the guidance of Professor Masanobu Hasatani of Nagoya University, in cooperation with Maekawa Mfg. Co. Ltd. Since the unit showed stable performance in over 2,500 hours of field testing conducted at a beverage plant in Aichi prefecture, Maekawa Mfg. Co. Ltd. will begin taking orders for sales in mid-November 2003.

A great amount of hot wastewater is generated from manufacturing processes in a variety of factories. Each year the heat of such wastewater produced in Japan is equivalent to 17.5 trillion kcal (the same calorific content as 10 million barrels of oil). However, more than 60% of this wastewater is discharged at temperatures below 60°C, with no technologies available to make use of it. H-ADREF is the world's first energy-saving unit that can reuse the thermal energy of low-temperature wastewater.

An absorption-type refrigeration unit is a cooling and air-conditioning unit that produces cold water of about 10°C using the heat of vaporization (the phenomenon in which water takes heat energy from its surroundings when it evaporates). When an absorbent (silica gel) absorbs water vapor in an airtight container and the interior pressure drops, evaporation of water is facilitated. The resultant heat of vaporization helps to produce cold water, with the repetition of the processes of absorption and dehydration of the absorbent resulting in continuous cold-water generation.

Previously, when hot wastewater was used as a heat source to dehydrate an absorbent, water hotter than 60°C was required, with an optimum temperature of 75°C. H-ADREF has made it possible to use low-temperature wastewater effectively, by incorporating a suction pump into the unit that intakes water when heated, and through the use of both exhaust heat and electricity as the power source for the refrigeration unit. This unit is designed to use water at 55°C, 20 degrees lower than that used in traditional units, with an effective temperature range of 40 to 70°C. The device can produce cold water with a cooling capacity more than ten times greater than the commercial power it consumes.

Finding the speed at which an absorbent absorbs and releases water vapor and identifying the optimum suction pump system and method of operation all contributed to the successful commercialization of the unit. We anticipate that we will be able to promote this device as an energy-saving, water-saving appliance that will produce cold water efficiently through the reuse of low-temperature wastewater generated at food, beverage and chemical factories.

Main features

  1. (1) Low-temperature exhaust heat, previously useless, now serves a functional purpose
Low-temperature exhaust heat (below 60°C), previously discarded, can now be used effectively, even if the temperatures and amounts of such heat vary.
  1. (2) Cost of operation of the highly efficient, energy-saving unit is less than half that of conventional devices.
The H-ADREF has a cooling capacity more than 10 times greater than the power consumption of the unit, resulting in drastic energy savings (with a coefficient of performance* of over 10). The cost of operation of the unit is thus more than 50% less than that of units that do not use exhaust heat.
* Coefficient of performance (COP): Cooling capacity divided by power consumption. The COP of conventional refrigeration units is approximately 5.
  1. (3) Friendly to the environment
The refrigerant used to transfer heat is water, which doesn't deplete the ozone or contribute to global warming, unlike chlorofluorocarbons (CFC). It also offers reduced emissions of carbon dioxide through its energy-saving features.