APPLICATIONOF SMART SENSORS TO REDUCE ENERGY USAGE IN AIR CONDITIONING 1.
ABSTRACT In this study, phones, wearable/portabledevices, detectors that detect temperature and human motion are integrated assmart sensors to reduce the amount of energy used for air conditioning andventilation. Advanced Smart sensors get input feedback from mobile phones, smartgadgets and portable devices placed on human body. The data obtained can beused to adjust(increase or decrease) air conditioners and ventilation systemsin advanced to the occupants’ intentions. Outcomes indicate that the indoortemperature can be controlled faultlessly with errors of less than ±0.1 °C.Fast chill off can be obtained within 2 to 3 minutes to the optimized indoorcapacity after occupants enter a room. It’s likewise noted that within 2 houroperation the total compressor yield or output of the smart air conditioner is 48.4%less than that of the particular case using On-Off control.
The advanced smartair conditioner with wearable or portable gadgets could identify those humantemperature and activity during sleep to determine the sleeping state andadjusting the sleeping function flexibly. The sleeping or rest function optimizedby the smart aeration and cooling system with wearable units could reduce theenergy usage up to 46.9% and keep the human health. The presented smart airconditioner could accomplish a comfortable environment and achieve the goals ofenergy conservation and environmental protection. 2.
DEVELOPMENT OF HEATING, VENTILATION AND AIR CONDITIONING TECHNOLOGY TO REDUCEENERGY CONSUMPTION. For a higher quality and comfortable presentday modern lifestyle, individuals depend around air conditioners (ACs) muchmore than the past. In both developing and developed countries, ACs tends to increasethe occupancy ratio of building areas. This also leads to a fast and rapiddevelopment in the energy consumption by Air conditioning systems. According tostatic data, HVAC very nearly expended half of the energy in buildings and 20%of the total national energy utilization. Therefore, it is vital to diminishthe energy consumption of Ai Conditioning systems in private residential aswell as commercial buildings. The methods of creating new energy-efficientequipment, applying complex and unpredictable control strategies, using solarenergy as a new vital energy source, etc., are all being considered for savingenergy in ACs.
Among them, applying control methodologies may be the moreeconomical and efficient strategy. The outcomes show that the energy consumptionof pumps can be minimized by using these control methods. A feedback controllerfor ACs is designed and improves the energy efficiency of aeration and coolingsystems. Experimental outcomes show that this method can come with a bettercoefficient of performance of the Air Conditioner and a comfortable indoorenvironment even in very hot and humid uncomfortable weather. For multi-unit AirConditioners, a fuzzy logic control method is used to control the operationalnumber of compressors and fans to enhance energy proficiency.
The pastresearches of applying control methodologies on ACs are mainly based on thedifference of parameters and cause the reaction. This is one kind of passiveresponses and may not be suitable for human comfort and health. The developinghistory of Air Conditioners is connected to the efficiency, technology, humancomfort, and energy utilization. Air Conditions’ progress includes window type,split type, fixed frequency, convertible frequency, and the recently presentedsmart type. In the 1990s, to reduce noise and satisfy the users, window typeair conditioners were modified to the split type by moving the compressoroutside the occupancy area. Since 2000, the high oil price and the need forenergy conservation have forced the control of compressors to be changed andimproved from fixed frequency to convertible.
The fixed frequency control ofcompressors adopts full power as the On-Off output, and causes temperaturechanges and waste of energy. However, by utilizing an electronic expansionvalve, the modified convertible frequency control can adjust the compressoroutput and the flow rate of refrigerant according to the indoor thermal massfor energy conservation. Since 2010, smart phones, tablets, personal computers,and cloud computing and 4th generation (4G) communication in 2014 weregenerally used and have resulted in an information revolution. By utilizing communicationtechnologies, the adjustment of air conditioners is not only a single feedbackof setting information. A smart air conditioning system can be combined with aninfrared sensor for human position sensing, meteorological webs for outdoorweather information, wearable devices for human activity and intentionawareness.
Henceforth, air conditioners are expected to alter the indoortemperature efficiently considering human comfort and energy conservation. 3. MATHEMATICAL MODELLING OFAIR CONDITIONING CONTROL AND ENRGY USAGE This study centered onsmart control of air conditioners utilizing mobile phones and wearable gadgetsas smart sensors. It’s the most up to date trend in air conditioner development.Before presenting the design, a mathematical model of air conditioning controlis derived from fundamental theorems.
That would help to illustrate thefollowing concepts clearly and plainly. The basic operating principle of theair 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 toa higher pressure vapor, also known as superheated vapor; (2) eliminating heat fromthe system by either circulating water or air and is condensed into saturatedliquid; (3) Undergoing an unexpected decrease inpressure through the throttle and expansion process, and becoming a liquid andvapor refrigerant mixture with lesser temperature and pressure; (4) Absorbing the heat of an enclosed space orspace by a circulating fan in the evaporator and expands into the saturatedvapor; (5) Vapor is routed back into the compressorto complete cooling cycle by cycle. The vapor cycleincorporates compression, heat extraction, expansion, and heat absorption. This process is accomplished by thecompressor, condenser, expansion valve and evaporator.
The more explained operatingprinciples of the vapor cycle include the variation of temperature, pressure,enthalpy and entropy. For a traditional window type air conditioner, these 4devices were installed in an air conditioner to carry out the vapor cycle andchill down the closed area. Almost been 90% of the traditional window typeairconditioners are replaced by the split type now. The compressor andcondenser of the split type air conditioner are integrated in the outdoor unitto avoid the compressor noise.
The expansion valve and evaporator are organizedas the indoor unit. One of the many advantages of split AC is the fact that itproduces less noise, and this feature has made it the main trend of air conditioners for homeand business purposes. 4. SMART CONTROLLER DESIGNBASED ON SMART SENSORSBefore the introduction of the smartcontrol, the On-Off and Inverter control are perfectly described in thefollowing two sub-sections.
Both of them, compared with smart control,represent the difference causing control. Then the smart sensors, includingportable phones, wearable gadget units and other sensors, are introduced. Thesewill be the key components to decide human intentions. Finally, the outline ofa smart controller based on smart sensors and gadgets is illustrated to showthe intention causing control.4.1.On-Off Control of the Fixed Frequency Air ConditionerThe meaning of fixed frequency is thecompressor of the AC works in the fixed rotation velocity.
The association betweenthe rotation speed of motor and electrical frequency can be explained as:Speed (rpm) =(120*f) (1-d) p f = theelectrical frequency p = is the magnetic poles of motord = is therotary slip difference (d = 0 under zero loading). Thetemperature inside is kept stable by operating the compressor to on and offpositions, when the motor works in the fixed rotation speed and the indoor airconditioning load is less. This method of operating the Air Condition is alsomentioned as On-Off control. In themethod of On-Off control, the fixed frequency air conditioner turns on thecompressor when the return air temperature is higher than the set one, andturns it off when it’s the opposite. By doing this, the refrigerant would flowthrough the condenser and evaporator for heat exchanging with the indoor andoutdoor air to keep the indoor temperature stable. 4.
2.Inverter Control of the Convertible Frequency Air Conditioner The main air conditioning product for energyconservation is the convertible frequency Air conditioner. It maybe characterizedas the situation where the rotation speed of the motor could be adjusted orchanged according to our wish for regulating the refrigerant energy output bychanging the input electric power frequencyComparingthe convertible frequency type with the fixed frequency could first rectify the60 Hz electricity into the direct current type, and then by using pulse widthmodulation , modulate the frequency of output electricity .
As stated by thefeedback temperature difference, the AC could provide the air flow of stabletemperature to control the temperature of indoor space by adjusting therefrigerator flow. 5.SMART SENSORSSmartsensors, including smart versatile phones, wearable units and other sensors,are introduced in the market now.
They are the key components of smart controlfor detecting the human’s intention and passing it on to the system. Mobilephones would provide occupants’ information by incorporating to the GPS andpersonal schedule for collecting the position and intentions of the person. Theair conditioner could cool down the indoor temperature fast before theoccupants enter.The wearablegadgets and their provisions are predicted to have a sudden increase in thecoming future. Gadgets that are wearable , such as watches or bracelets, may beadopted for detecting the human sleeping state as the feedback signals of thesleeping function.
The accelerator could detect the acceleration between 10 and10?6 g, the velocity between 10 and 1.67 ×10?9 m/s, and the displacementbetween 10 and 2.78 ×10?13 m. It can collect human motion information andfeedback to the smart air conditioner for further control. 5.
1.Smart Control Based on Smart Sensorscounting theexamination of the fixed and convertible frequency control schemes, thequantitative investigation of the smart control based on the smart sensors is thefundamental focus in this paper. Smart control, in view of the information collected by the useof mobile phones and wearable gadgets, strengthens the connection withoccupants and carries out the intention causing control. It might incorporate thefollowing aspects: (1) Mobile telephones with GPS and individual timetables,for recognizing the tenants’ position and intentions, could anticipate theoccupants’ intention of entering the enclosed area. At this minute, the compressor,which is off in the usual situation, could turn on in the full power. Beforeentering, the circling fan turns on at the highest speed, and the air deflectorswings for 10 min to enhance the air circulation.
consequently, smart controlmay enable the enclosed space could be chilled off quickly after the tenantsenters. (2) The arm ornament with the accelerator could detect the developmentof tenant while sleeping. After the occupant falls into a deep sleep, the airconditioner would increase the inside temperature lightly to avoid energyconsumption. The smart air conditioner could adjust the compressor outputactively according to the occupants’ active intention (going home) and passiveone (falling into a deep sleep) for the goals of human comfort and energyconservation. The smart air conditioner includes the following devices: (1) Air conditioner with changablerefrigeration power; (2) Novel sensors capable of collaboratingwith inhabitants; (3) Communicatingunits for cell phone and network. Figure demonstratesthe controlling structure of smart air conditioner, including ventilationsystem, temperature sensor, IR indicator, mobile phone and wearable gadgets.
Thecontrol structure of the smart aeration and cooling system in Figure utilizes amulti-sensor framework to achieve smart control. The indoor infrared sensor candistinguish peoples’ position and carry out the air flow direction control. Cellphones with GPS and personal timetable can be utilised to detect theinhabitants’ position and intention.
Wearable units can be the bracelet withthe accelerator. It understands the movement of occupants while sleeping. Afterthe occupant fallings into a deep sleep, the smart air conditioner would upliftthe indoor temperature lightly to avoid energy utilization.
Figure- Thecontrol plan of a smart ventilation system with Inverter control: differentfrom the fixed and convertible frequency air conditioner with differencecausing control, it’s an intention causing control that adjusts the compressoroutput effectively based the occupants’ active intention (going home) andpassive one (falling in a deep sleep) for the goals of human comfort and energyconservation.