APPLICATION OF SMART SENSORS TO REDUCE ENERGY USAGE IN AIR CONDITIONING 1. ABSTRACT In this study, phones, wearable/portable devices, temperature detectors and human motion detectors are integrated as smart sensors to reduce the amount of energy used for air conditioning and ventilation. Advanced Smart sensors get input feedback from mobile phones and portable devices placed on human body.
The data obtained can be used to adjust air conditioners and ventilation systems in advanced to humans’ intentions. Outcomes indicate that the indoor temperature can be controlled faultlessly with errors of less than ±0.1 °C. Fast chill off can be obtained within 2 minutes to the optimized indoor capacity after occupants enter a room. It’s likewise noted that within 2hour operation the total compressor yield of the smart air conditioner is 48.
4% less than that of the particular case using On-Off control. The advanced smart air conditioner with wearable or portable gadgets could identify those human temperature and activity during sleep to determine the sleeping state and adjusting the sleeping function flexibly. The sleeping or rest function optimized by the smart aeration and cooling system with wearable units could reduce the energy usage up to 46.9% and keep the human health. The presented smart air conditioner could accomplish a comfortable environment and achieve the goals of energy conservation and environmental protection. 2.
DEVELOPMENT OF HEATING, VENTILATION AND AIR CONDITIONING TECHNOLOGY TO REDUCE ENERGY CONSUMPTION. For a higher quality and comfortable present day modern lifestyle, individuals depend around air conditioners (ACs) much more than the past. In both developing and developed countries, ACs tends to increase the occupancy ratio of building areas.
This also leads to a fast and rapid development in the energy consumption by Air conditioning systems. According to static data, HVAC very nearly expended half of the energy in buildings and 20% of the total national energy utilization. Therefore, it is vital to diminish the energy consumption of Ai Conditioning systems in private residential as well as commercial buildings. The methods of creating new energy-efficient equipment, applying complex and unpredictable control strategies, using solar energy as a new vital energy source, etc.
, are all being considered for saving energy in ACs. Among them, applying control methodologies may be the more economical and efficient strategy. The outcomes show that the energy consumption of pumps can be minimized by using these control methods.
A feedback controller for ACs is designed and improves the energy efficiency of aeration and cooling systems. Experimental outcomes show that this method can come with a better coefficient of performance of the Air Conditioner and a comfortable indoor environment even in very hot and humid uncomfortable weather. For multi-unit Air Conditioners, a fuzzy logic control method is used to control the operational number of compressors and fans to enhance energy proficiency. The past researches of applying control methodologies on ACs are mainly based on the difference of parameters and cause the reaction. This is one kind of passive responses and may not be suitable for human comfort and health.
The developing history of Air Conditioners is connected to the efficiency, technology, human comfort, and energy utilization. Air Conditions’ progress includes window type, split type, fixed frequency, convertible frequency, and the recently presented smart type. In the 1990s, to reduce noise and satisfy the users, window type air conditioners were modified to the split type by moving the compressor outside the occupancy area. Since 2000, the high oil price and the need for energy conservation have forced the control of compressors to be changed and improved from fixed frequency to convertible.
The fixed frequency control of compressors adopts full power as the On-Off output, and causes temperature changes and waste of energy. However, by utilizing an electronic expansion valve, the modified convertible frequency control can adjust the compressor output and the flow rate of refrigerant according to the indoor thermal mass for energy conservation. Since 2010, smart phones, tablets, personal computers, and cloud computing and 4th generation (4G) communication in 2014 were generally used and have resulted in an information revolution. By utilizing communication technologies, the adjustment of air conditioners is not only a single feedback of setting information. A smart air conditioning system can be combined with an infrared sensor for human position sensing, meteorological webs for outdoor weather information, wearable devices for human activity and intention awareness. Henceforth, air conditioners are expected to alter the indoor temperature efficiently considering human comfort and energy conservation. 3. MATHEMATICAL MODELLING OF AIR CONDITIONING CONTROL AND ENRGY USAGE This study centered on smart control of air conditioners utilizing mobile phones and wearable gadgets as smart sensors.
It’s the most up to date trend in air conditioner development. Before presenting the design, a mathematical model of air conditioning control is derived from fundamental theorems. That would help to illustrate the following concepts clearly and plainly. The basic operating principle of the air conditioner (aeration and cooling system) is the vapor cycle introduced by thermodynamics. The vapor cycle includes the following steps: (1) The saturated refrigerant is compressed to a higher pressure vapor, also known as superheated vapor; (2) Rejecting heat from the system by either circulating water or air and is condensed into saturated liquid; (3) Undergoing an unexpected reduction in pressure through the throttle and expansion process, and becoming a liquid and vapor refrigerant mixture with lower temperature and pressure; (4) Absorbing the heat of an enclosed space or space by a circulating fan in the evaporator and expands into the saturated vapor; (5) Vapor is routed back into the compressor to complete cooling cycle by cycle.
The vapor cycle incorporates compression, heat extraction, expansion, and heat absorption. This process is accomplished by the compressor, condenser, expansion valve and evaporator. The more explained operating principles of the vapor cycle include the variation of temperature, pressure, enthalpy and entropy. For a traditional window type air conditioner, these 4 devices were installed in an air conditioner to carry out the vapor cycle and chill down the closed area. The traditional window type air conditioner has almost been 90% replaced by the split type now.
The compressor and condenser of the split type air conditioner are integrated in the outdoor unit to avoid the compressor noise. The expansion valve and evaporator are organized as the indoor unit. One of the many advantages of split AC is its quietness, and this feature has made it the main trend of air conditioners for home and business purposes.
4. SMART CONTROLLER DESIGN BASED ON SMART SENSORSBefore the introduction of the smart control, the On-Off and Inverter control are perfectly described in the following two sub-sections. Both of them, compared with smart control, represent the difference causing control. Then the smart sensors, including portable phones, wearable gadget units and other sensors, are introduced.
These will be the key components to decide human intentions. Finally, the outline of a smart controller based on smart sensors and gadgets is illustrated to show the intention causing control.4.1. On-Off Control of the Fixed Frequency Air ConditionerThe meaning of fixed frequency is the compressor of the AC works in the fixed rotation velocity.
The association between the rotation speed of motor and electrical frequency can be explained as:Speed (rpm) = (120*f) (1-d) p f = the electrical frequency p = is the magnetic poles of motord = is the rotary slip difference (d = 0 under zero loading). The temperature inside is kept stable by operating the compressor to on and off positions, when the motor works in the fixed rotation speed and the indoor air conditioning load is less. This method of operating the Air Condition is also mentioned as On-Off control. In the method of On-Off control, the fixed frequency air conditioner turns on the compressor when the return air temperature is higher than the set one, and turns it off when it’s the opposite. By doing this, the refrigerant would flow through the condenser and evaporator for heat exchanging with the indoor and outdoor air to keep the indoor temperature stable.