Evaporative Cooling-mechanical Refrigeration Composite Air Conditioning System Control Program Design

Evaporative cooling technology is a kind of high efficient and economic cooling mode, the main use of water evaporation heat absorption cooling air, when air temperature down to requirements, can be used as supply air on indoor for air conditioning. Evaporative cooling water as the carrier of cold quantity, to reduce greenhouse gas and CFC emissions. At the same time, the evaporative cooling technique using dry air, can be reduced to the electric power demand, to achieve the goal of energy saving. At present, the evaporative cooling technology has set up a file in the northwest of our country, widely used in humidity area due to climate factors, in the summer requires a combination of mechanical refrigeration system to provide for the common cold quantity, its application range is also gradually to promotion.Along with the improvement of the building intelligence, central air conditioning automatic control technology is also obtained the rapid development. The central air conditioning system automatic control task is the largest in energy saving and safety production conditions, make to the actual load to adapt, to meet the production process and the people in work and in life to the requirement of air parameters.This topic to a building xi’an dry condition fan-coil unit plus fresh air half a centralized system as a controlled object, the main analysis and research of the system of automatic control scheme.In order to in-depth design evaporative cooling-the of mechanical refrigeration composite air conditioning system building control scheme. First of all, analyses the moderate humidity area evaporative cooling-mechanical refrigeration compound air conditioning system working principle.Evaporative cooling high temperature water chillers in summer for the system to provide24℃high temperature cold water and air source heat pump for the system to provide the7℃of frozen water mixed into18℃, provide sensible heat end, in order to achieve the interior design requirements.Winter air source heat pump alone start as heat source.Transitional seasons use fresh air unit for the indoor air supply new air. Meanwhile,analyzed each season central air conditioning system air handling process. Design scheme selection Johnson control system distributed control way to direct digital apparatus design the whole system control. Dry condition fan coil in every office decentralized control, by using personnel according to their own comfortable regulating air volume and temperature.The main task for evaporative cooling high temperature water chillers and evaporative cooling fresh air unit design control scheme,the entire program is mainly related to temperature monitoring,alarm monitoring, valve interlocking control, fan and water pump control.According to the system’s need and point table selection system required hardware equipment.The writing system to run the program, make whole evaporative cooling-mechanical refrigeration compound air conditioning system to achieve the best operation condition at the same time do the purpose of saving energy economy.Use of Johnson buildings automatic control system design of the evaporative cooling-mechanical refrigeration composite air-conditioning system of monitoring interface, for different seasons run mode design the summer, the transitional seasons, winter monitoring interface. In the fresh air unit with hot and cold source on the monitor interface, set up observation points of the operational status of the system components.