The present invention relates to air-conditioning cooling apparatus and more particularly pertains to an air-conditioning system with full heat recovery.
Following the increasing popularity of air-conditioners, the air-conditioning industry has been fast developing in the past decade. However, the increasing popularity of air-conditioners exerts enormous pressure on the existing insufficient electricity supply facilities. Statistics show that electricity consumption-of-air-conditioners amounts to 35% of the total electricity consumption of an office building. The operational costs of air-conditioners are huge. Developing air-conditioning facilities of effective energy saving capability has therefore been a development trend in the air-conditioning industry.
The existing air-conditioners are mainly divided into two types, namely air-cooled air-conditioners and water-cooled air-conditioners. Air-cooled air-conditioners utilize outdoor air directly as the cooling agent to cool the apparatus. Since the refrigeration operation of air-conditioners is mainly in the seasons of higher temperature, the refrigeration efficiency of directly using outdoor air for cooling is therefore relatively low, where the COP (coefficient of performance) is maintained at around 2.0. It can be seen that this type of air-conditioners is of high energy consumption. However, air-cooled air-conditioners dominate the market because of the convenience in installation and the flexibility in location. Water-cooled air-conditioners utilize water as the cooling agent and bring the exhaust heat of the refrigeration system to the cooling tower. Heat is then discharged outdoor by the cooling tower. Since the cooling tower can lower the temperature of cooling water to approximately the outdoor wet-bulb temperature, the refrigeration system operates with cooling water of outdoor wet-bulb temperature, thereby increasing the refrigeration efficiency of the water-cooled air-conditioners, where the COP can reach 3.8 to 4.0. Nevertheless, since water-cooled air-conditioners are installed additionally with a cooling tower and a cooling pump, the overall energy consumption of the system and the costs of the apparatus increase. Moreover, for the purposes of heat radiation, traditional cooling towers usually use water sprinklers to spray water evenly. Water drops from this type of sprayers are relatively small. Further, there are relatively strong winds in the cooling tower. Therefore, it is common for water drops to “fly” out of the cooling tower during its operation as small water drops are carried by strong winds to spill out from the tower directly. This water spillage amounts to over 50% of the total water consumption of the cooling tower, while the water used for actual evaporation and heat radiation is less than 50%. Furthermore, the air-conditioners produce large volume of condensate during the refrigeration process. Known skills are to directly discharge the condensate that is produced. Since the temperature of condensate is as low as 10° C. to 15° C., the cooling energy loss is relatively high. If the condensate can be directly recycled to assist cooling, the temperature of cooling water can be lowered and energy can be saved, and this can greatly reduce the consumption of cooling water.
In addition, when the air-conditioner is used, for the purposes of satisfying the hygienic requirements of indoor air, fresh air has to be supplied continuously to the air-conditioning area. In existing air-conditioning systems, fresh air load amounts to around 30% of the total air-conditioning load and the energy consumption is high. To reduce the total load, fresh air reduction methods are often used, which lead to poorer air quality in the air-conditioning area and fail to satisfy the hygienic requirements. Further, an exhaust system that discharges some of the indoor air to the outside has to be installed to facilitate indoor air exchange. The discharged air is a cooling air source of low temperature and humidity. Its temperature is usually relatively low at 25° C. to 28° C. Its relative humidity is also low at 60% to 70% and its wet-bulb temperature is even as low as 20° C. to 23° C. The existing air-conditioners of air-conditioning systems fail to utilize this cooling energy and thus lead to wastage directly.