Power Consumption Of Air Conditioner Research Articles

Thermosensitive Scattering Hydrogels Based on Triblock Poly-Ethers: A Novel Approach to Solar Radiation Regulation.

Energy conservation in buildings is paramount, especially considering that glass accounts for 50% of energy consumption. The solar heat gain coefficient (SHGC) of glass is a critical energy-saving index for transparent structures. However, the fixed SHGC of ordinary glass makes it difficult to provide both summer shading and winter heating. In this study, we synthesized a hydrogel with a thermosensitive scattering (TS) property using triblock polyether and acrylamide. This hydrogel can realize the transition of clearness and atomization based on the temperature. When sealed within a glass cavity, it exhibits a high SHGC of 0.682 in its transparent state and a low SHGC of less than 0.31 when atomized. The lower critical solution temperature (LCST) of the TS glass can be adjusted from 0 to 70 °C to suit different regions. The photothermal properties of the material remained stable after 200 hot and cold cycles and 200 h of ultraviolet irradiation. This glass can prevent solar radiation from entering the room in summer, thereby reducing air conditioning usage and power consumption. In winter, it allows solar heat radiation to enter the room, minimizing the need for artificial heating. Its adaptable temperature design makes it an excellent solution for designers to create energy-efficient building exteriors.

The Mathematical Modeling and Performance of Sky Radiative Coolers

Sky radiative cooling is a kind of passive cooling technology that uses the “atmospheric window” to emit the object’s own heat to the low temperature of outer space; this technology has low energy consumption, no pollution, and other useful characteristics, so in recent years it has attracted widespread attention. The cooling effect of the sky radiative cooler is mainly affected by the constantly changing outdoor ambient temperature. In addition, the structure of the radiative cooler itself also means that its radiative cooling power undergoes obvious changes. Here, we utilized COMSOL simulation software to establish a numerical heat transfer model for radiative cooling, aimed at investigating the influencing factors on the sky radiative cooler and methods to enhance the structure of the radiative cooling. This study discusses outdoor ambient wind speed, the inlet flow rate of the cooler, installation angle of the cooler, and different cooler structures. Based on simulation results, it is observed that, for varying wind speeds, when the ambient radiation temperature is higher than the surface temperature of the cooler, a larger ambient wind speed leads to a poorer refrigeration effect. The maximum temperature difference in surface temperature at wind speeds of 0 m/s and 4 m/s is 0.59 °C. When the ambient temperature is lower than the surface temperature of the cooler, a smaller wind speed results in a greater net refrigeration power. The maximum temperature difference in this scenario is 0.32 °C. The net refrigeration power of the radiative cooler increases with an increase in water flow rate. As the water flow rate increases from 0 L/min to 5 L/min, the net refrigeration power increases from 25 W/m2 to 200 W/m2 and gradually stabilizes. Considering the radiative impact of the cooler on the surrounding environment, as the installation angle increases from 0° to 90°, the surface temperature of the cooler first increases and then decreases, reaching its highest temperature of 29.26 °C at 45°. The surface temperature of the cooler varies with the thickness of the air sandwich, increasing from 1 cm to 12 cm, and then decreasing. The lowest temperature of 23.4 °C is achieved at a thickness of 8 cm. The increase in the fin structure on the surface of the radiative cooler leads to a decrease in its refrigeration performance, and the difference between the inlet and outlet temperatures of the radiative cooler with a flat plate structure is always greater than that of the finned plate, and the difference in the average radiance is 23.52 W/m2. Finally, the energy-saving effect of the sky radiative cooling composite system is analyzed. Taking a typical small office building as an example, an energy consumption analysis model is set up, and the energy consumption of the composite system is simulated in four cities with different climates, using EnergyPlus software (version 8.6); the system’s power consumption is the largest in hot and humid climates. Compared with the traditional vapor-compression refrigeration system, the composite system reduces air conditioning power consumption by 25.7%, 32.5%, 37.1%, and 44.8% in Guangzhou, Shanghai, Jinan, and Shenyang, respectively. The main innovations of this paper include analyzing and studying the influence of the tilt angle change of the radiative plate on the refrigeration performance of the cooler and the relationship between the surrounding buildings, adding air sandwiches and ribs to the radiative cooler to analyze the influence of convective heat transfer on the refrigeration effect, which plays a guiding role in the design and research of the sky radiative cooler.

Load rebound suppression strategy and demand response potential of thermal storage HVAC systems: An experimental and simulation study

The problem of power imbalance caused by the large power consumption of heating, ventilation and air-conditioning (HVAC) units in the summertime can be alleviated by building demand response (DR) strategies. However, after DR, load rebound will occur due to the sudden increase in demand. Meanwhile, there is a general lack of information on effective DR strategies. To study the DR potential and load rebound suppression strategies of HVAC systems, nine operation strategies were devised and applied experimentally. The physical experiments were conducted on a central air-conditioning system to investigate control strategies such as regional temperature reset, active energy storage, cold source unit activation and deactivation, as well as pre-cooling. Additionally, a simulation model was developed utilizing TRNSYS. DR evaluation indices, such as duration, power reduction capability, system operation cost, etc. were applied. The experimental results show that after a water storage tank is added as a buffer tank, the start and stop times of the air source heat pump were reduced from 46 to 6. Utilizing the thermal inertia of building and HVAC system, while ensuring personnel's thermal comfort, the DR participation time can be extended to 40–50 min. This will result in an 8.9 %–12.6 % reduction in power consumption. The simulation results show that with active energy storage added, HVAC system's DR participation time can be increased to about 120 min, the maximum power consumption can be reduced by 23.4 %, and the maximum operating cost can be reduced by 21.7 %. The study shows that a slow recovery strategy and the extension of DR control time can limit load rebound effectively. From the result of load rebound suppression effect, if the load rebound suppression strategy is not adopted, the power after DR will be 3.7 % higher than that pre-DR; the load rebound suppression strategy is adopted, which is 3.6 % lower than that pre-DR. By implementing the proposed DR strategies, the issue of frequent activation and deactivation of refrigeration units can be effectively mitigated. This will greatly alleviate the power supply and demand contradiction, while also effectively suppressing the load rebound effect to prevent a secondary peak in power consumption.

Air conditioning energy consumption measurement and saving strategy analysis for an office building in hot summer and cold winter area

ABSTRACT The energy consumption of different air conditioning systems varies greatly. In order to analyse the energy consumption status and energy-saving potential of air conditioning in existing office buildings, this paper takes an existing office building in hot summer and cold winter area as an example. The office and air conditioning energy consumption were continuously measured. The air conditioning energy consumption analysis model was established. With the measured data as input, the simulation calculation of the annual air conditioning energy consumption was carried out. The results showed that the measured value was quite different from the recommended value of the building energy efficiency standard. Changes in indoor air temperature or fresh air volume had a significant impact on air conditioning energy consumption. When the indoor set air conditioning temperature was 22°C in summer and 22°C in winter, the fresh air volume increased from 0 to 180 m3/(p·h), the increase of air conditioning power consumption reached 109.9% and 115.2%, respectively. The energy-saving envelope of the office building can obtain about 15% of the energy-saving benefits. However, users’ adjustment of operating parameters such as fresh air volume and indoor design temperature can easily lead to energy loss greater than that of energy-saving envelope.

Study on occupant behaviour using air conditioning of high-rise residential buildings in hot summer and cold winter zone in China

Over the past two decades, the electricity consumption of residential air conditioning (AC) has increased by 13.4 times. Moreover, carbon emissions from building operations remain high. Occupant behaviour related to AC operation is the most significant factor affecting the energy consumption of residential ACs. Hence, in this study, occupant behaviour towards using air conditioning in high-rise residential buildings was analysed to provide suggestions for increasing the AC usage efficiency. Annual data on the AC power consumption, indoor temperature, and humidity of typical high-rise residential buildings in hot summer and cold winter zones in China were collected. Five target parameters—AC opening rate, AC standby rate, start–stop time, start–stop temperature, and stable temperature—were statistically analysed. The results reveal that the AC start–stop time follows a normal distribution. The start and stop times of the AC during the cooling period are 22:32 and 7:05 the next day, respectively, whereas during the heating periods these values were 20:42 and 23:02 or 7:56 the next day, respectively. The standard deviation of the time distribution of AC starting or stopping at night is larger than that during the day. The AC start-up temperature followed an exponential distribution. The indoor temperature during the cooling and heating periods is more than 29.42 °C and less than 11.08 °C, respectively. The opening rate of the room AC is 80 %.

Experimental analysis of airflow uniformity and energy consumption in data centers

Temperature and airflow uniformity are experimentally investigated in this research study along with energy consumption analysis on the laboratory container size small data center. A raised floor plenum (RFP) data center system of size 6 (L) × 3.1 (W) × 2.3 (H) m with one Computer Room Air Handler (CRAH), two rows and each row contains five racks, five 8U simulator cabinets in each rack was constructed to test partial and closed cold aisle containment (CAC). Seven different cases were investigated with variables of perforated tiles (32%, 50 % & 70%), CRAH fan speed (60 Hz, 42 Hz), chiller return water temperature (CRWT) (15 °C & 17 °C) and heating load (full 50 kW, 75% load 37.5 kW). These cases were further analyzed using Rack Cooling Index (RCI) and Supply Heat Index (SHI) along with power consumption scenarios in terms of Coefficient of Performance (COP) and Power Usage Effectiveness (PUE). The uniqueness of this study is experimental investigations of system COP and PUE analysis for a wide range of important variables for partial and closed CAC. It was found that 50% porous tile provided the best airflow and temperature uniformity for the case of partial containment with full and 25% reduced heat load along with full and 30% reduced CRAH speed respectively. Slight recirculation was observed during the reduced CRAH fan speed case at the corner edge of data racks. However, due to additional supply airflow usage, these recirculation’s were within the acceptable SHI. Reduction of CRWT reduces the total Heating Ventilation and Air Conditioning (HVAC) power consumption and improves the overall system COP.

Experimental Investigation of Energy Efficient Room Air Conditioners for Mini-Stores

An experimental investigation of energy efficiency room air conditioners for the mini-stores was presented and illustrated in the paper. The experiment has been carried out in two well-insulated rooms with two different compressor technologies (fixed-speed and inverter) and essential equipment in a laboratory located at the School of Heat Engineering and Refrigeration (Hanoi University of Science and Technology). The authors conducted the test with three different heat load categories and weather conditions to examine the energy efficiency based on several factors such as room temperature and power consumption of air conditioner from records. Results show the significant effect of various aspects on the efficiency and the behaviour of air-cooled air conditioners including the indoor heat load and the outdoor temperature. The results also suggest a suitable cooling capacity choice that helps improve the energy efficiency of air conditioners besides the technical data such as CSPF (or SEER) and power consumption.

Study on productivity of office workers and power consumption of air conditioners in a mixed-mode ventilation building during springtime

The thermal environment in offices affects the productivity of workers; thus, it is important to adjust the thermal environment appropriately with heating, ventilation, and air conditioning. However, there is an urgent need to reduce the amount of energy used in the building sector for cooling, which has been rising. Mixed-mode ventilation has attracted attention as a means of decreasing air conditioning power consumption and improving the satisfaction of office workers. In the present study, a measurement survey and a questionnaire survey were conducted during springtime to investigate air conditioning power consumption during mixed-mode ventilation and to elucidate the relationship between the use of mixed-mode ventilation and productivity. The power consumption on the mixed-mode ventilation floors was less than that on the mechanical ventilation floors in the measurement period when the average outdoor air temperature was 21 °C, with savings ranging from 3.1% to 70.6%, although it varied widely with the weather conditions. The relationship between the use of mixed-mode ventilation and productivity was analyzed using multilevel analysis (hierarchical linear model), a method that considers the data hierarchy. Mixed-mode ventilation improved the productivity of male participants by about 9.1%, suggesting that mixed-mode ventilation could both decrease air conditioning power consumption and improve productivity during springtime. However, the increase in productivity of female participants was about 0.5%, indicating that there may be differences depending on gender. The present study has practical implications for promoting mixed-mode ventilation as a means to reduce air conditioning power consumption in offices and improve productivity.

Advanced thermal environment and energy consumption calculation over time using combined energy simulation, computational fluid dynamics, and heat source model

We developed an unsteady computational simulation tool that sequentially inputs the calculated heat load to a heat source model to determine the coefficient of performance (COP) and power consumption of air conditioners. The accuracy of the energy consumption prediction was improved by incorporating the air-conditioning model into the coupled calculation of energy simulation and computational fluid dynamics as well as reproducing the behaviour of equipment efficiency. We conducted a comparative study in an office with a partition in the centre to investigate the effects of short circuits and heat accumulation. The experiments indicated a difference between the bulk temperature of the space and the input air humidity of the air conditioner of ∼2.0°C and 2.5 g/kg (DA), respectively. The coupled analysis confirmed that the power consumption of the bulk temperature/humidity input was ∼100 W and the COP error was ∼2, while the suction temperature/humidity input had high accuracy.

Electricity Consumption Forecast of High-Rise Office Buildings Based on the Long Short-Term Memory Method

Various algorithms predominantly use data-driven methods for forecasting building electricity consumption. Among them, algorithms that use deep learning methods and, long and short-term memory (LSTM) have shown strong prediction accuracy in numerous fields. However, the LSTM algorithm still has certain limitations, e.g., the accuracy of forecasting the building air conditioning power consumption was not very high. To explore ways of improving the prediction accuracy, this study selects a high-rise office building in Shanghai to predict the air conditioning power consumption and lighting power consumption, respectively and discusses the influence of weather parameters and schedule parameters on the prediction accuracy. The results demonstrate that using the LSTM algorithm to accurately predict the electricity consumption of air conditioners is more challenging than predicting lighting electricity consumption. To improve the prediction accuracy of air conditioning power consumption, two parameters, relative humidity, and scheduling, must be added to the prediction model.

Experimentally evaluation of split air conditioner integrated with humidification-dehumidification desalination unit for better thermal comfort, produce freshwater, and energy saving

The present experimental study aims to achieve the better indoor thermal comfort, produce freshwater, and energy saving. To investigate this idea, split air conditioner was integrated with solar assisted humidification-dehumidification (HDH) desalination unit, the HDH desalination unit was designed to produce the freshwater and also used as a pre-cooling unit to cool the condenser of split air conditioner in order to reduce a power consumption, increases the cooling capacity, and COP. To obtain the effect of utilizing the HDH desalination unit as pre-cooling unit on a performance of the split air conditioner, two operating cases were suggested to run the HDH unit and the split air conditioner. In the first operating case, the HDH unit was operated separately from the air conditioner. In the second operating case, the HDH unit was connected to the condenser of air conditioner to cool the condenser. Is this case the cold air leaving from the dehumidifier of the HDH desalination unit was used to cool the condenser of the split air conditioner. The results show that when the HDH desalination unit combined with the split air conditioner, (i) the saving in power consumption of air conditioner reached 18.4%, (ii) COP for the air conditioner improved by 48.5%, (iii) accumulative freshwater production reached 36.49 L day−1, and (iv) the improvement in GOR for utilizing the proposed hybrid system reached 60.9%.

Development of Air‐Conditioning Operation‐Planning Method for Large Spaces

When targeting large spaces, temperature distribution occurs due to air flow. Therefore, when evaluating the some state quantity values in large spaces using the single‐mass model, the evaluation values cannot be accurately evaluated. In our developed method, we analyze in advance flow distribution with high computational load and make contributed ratio of indoor climate (CRI). By using CRI for making air‐conditioning operation plan, the air conditioning power consumption and demand response (DR) amount can be quickly obtained. We also conducted an evaluation to compare the difference in these values between our developed method and using the single‐mass model. The air‐conditioning power consumption and DR amount of the developed method were smaller than those of the single‐mass model since it takes into account the temperature difference between upper and lower regions of space. It was also confirmed that the derived room temperature distribution by the CRI had an error within 1 °C compared with the evaluation using computer fluid dynamics (CFD). © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Comparison of energy consumption between non-inverter and inverter-type air conditioner in Saudi Arabia

Interest for air-conditioning systems (ACs) has exponentially expanded worldwide throughout the most recent couple of decades. Countries with booming economies including Saudi Arabia report high growth of sales of room air conditioners. With the expanded (GDP) and warming climates, interest for room air-conditioning systems is required to additionally increment. Meeting the expanded need for electricity energy will be a challenge. Expanded utilization of energy-efficient air conditioners impactsly affects lowering the electricity demand. In an ordinary AC, the blower runs at a fixed speed and is either ON or OFF. In an inverter AC, the compressor is consistently on; however, power drawn relies upon the demand for cooling. The speed of the compressor is adjusted appropriately. In this paper, the energy consumption of non-inverter and an inverter AC of the same capacity was assessed in an average office room, under comparative operating conditions, to find the differences in the energy saving, Carbon Dioxide (CO2) emission, and power consumption of air conditioner. Energy consumption was measured for about 108 days, which is from July 16th to October 31st, 24/7, and compared. The experiment is conducted with the same conditions and same capacity air conditioners (18,000 BTU). Results show that the day-by-day normal vitality utilization, the inverter will save up to 44% of electrical consumption compared to a non-inverter of 3471 kWh/year and 6230 kWh/year respectively. Furthermore, the Total Equivalent Warming Impact (TEWI) analysis shows that inverters can save 49% of CO2 emissions.

Design and analysis of cooling co-generation cycle using aqua-ammonia as working fluid

The world faces an emerging power crunch due to the increase in population and their needs. The per capita power consumption for refrigeration and air-conditioning in domestic applications is relatively high and it is at a peak during summer. Producing power and cooling output in a single cycle and to increase the thermal performance of the system is the main objective. A new cooling cogeneration cycle is proposed, and it is designed and analysed experimentally. The system is operated at three pressures viz condensing pressure, source and sink pressure. The plant comprises of pump, separator, superheater, turbine, condenser and absorber. The ammonia vapor at exit of separator expands through the turbine from generator pressure to condensing pressure to generate electricity. The same ammonia vapor is condensed to liquid and it is further expanded from condensing pressure to sink pressure to achieve the cooling effect. The power and cooling output of 1.8 kW and 8.04 kW are obtained experimentally at 0.25 of ammonia concentration. Maximum energy utilization factor (EUF) of 0.2 is obtained at the hot fluid supply temperature of 110 ⁰C and it can be further increased by raising the strong solution concentration of ammonia and lowering sink temperature. The proposed system is suitable for both domestic and industrial applications.

Energy Conservation and Consumption Reduction in Residential Quarters: Taking Cuihu Garden Residential District in Pingxiang City as an Example

This paper uses Auto-Revit for an energy assessment of Cuihu Garden Residential District located in Anyuan District, Pingxiang City, Jiangxi Province. Comparative analysis of building energy consumption before and after energy-saving renovation. Through simulation analysis, it can be concluded that replacing LED light sources, enhancing natural ventilation efficiency, and increasing green roof construction can effectively reduce building energy consumption. This article draws the following conclusions: Firstly, by replacing the LED light source, the energy of the residents in the community can be reduced by 65.2%; secondly, the combination of mechanical ventilation and natural shaft ventilation can reduce 73kWh of electricity in ten hours; finally, the green roof energy effectively alleviate temperature changes on the surface of the building, and indirectly reduce the power consumption of heating and air conditioning in the building. The research results can serve as a reference for the improvement of building energy efficiency in cities with subtropical monsoon climate regions represented by Pingxiang City. The direction of energy-saving improvement can be extended to inland small cities in the country and the world.

Plasmon-Enhanced Infrared Emission Approaching the Theoretical Limit of Radiative Cooling Ability.

Radiative cooling, a passive cooling technique, has shown great potentials in recent years to lower the power consumption of air conditioning. With the ever-increasing cooling power being reported, the theoretical cooling limit of such a technique is still unclear. In this work, we proposed a theoretical limit imposing an upper bound for the attainable cooling power. To approach this limit, we exploited the localized surface plasmon resonance (LSPR) of self-doped In2O3 nanoparticles, which enhance the emissivity in both primary and secondary atmospheric windows. The measured cooling power of poly(methyl methacrylate) (PMMA) films containing 4.5% In2O3 nanoparticles is very close to the limit with the closest value only about 0.4 W/m2 below the limit. Hopefully, this work may help the researchers better evaluating the performance of their device in the future and pave the way for achieving even higher radiative cooling powers during the daytime operations with the help of LSPR.

Doped semiconductor nanoparticles for possible daytime radiative cooling applications

Daytime radiative cooling has become a promising passive cooling technique in recent years, showing great potential in building-related applications to reduce the power consumption of air conditioning. Currently used mid-infrared emitters mainly rely on phonons in crystals, molecular vibrations in polymers (which have limited tunability) and other sophisticated photonic and plasmonic structures (which rely on expensive techniques). In this work, we propose the use of doped semiconductor nanoparticles as selective emitters, whose infrared optical properties can be readily tuned using the doping concentrations. The theoretical simulation shows that wide bandgap semiconductors with a bandgap greater than 3.5 eV can suppress solar absorption effectively. The plasma frequency fp should be approximately 2400 cm−1 to have enhanced emissivity in the atmospheric window for nanoparticles embedded in a medium with electric permittivity of 2.3. The complex refractive index of the metamaterial is calculated with the effective medium theory and the spectral and angular emissivity is estimated with the help of optical theories. A metamaterial containing 5% (volume fraction) doped ZnO nanoparticles is predicted to exhibit a cooling power greater than 100 W m−2 and a temperature drop of more than 10 °C under a wide range of ambient temperatures.

The effect of Al2O3/PAG nanolubricant towards automotive air conditioning (AAC) power consumption

The usages of Automotive Air Conditioning (AAC) today is vital because of the hot and humid climate. The AAC is used to provide comfort in the automotive cabin temperature, consequently, increases fuel consumption, and release significant amount of CO2, and greenhouse gas into the air. Nanotechnologies could be employed into AAC system via lubricant compressor which can decrease power consumption, eventually increase power saving. The main objective of this paper is to experimentally investigate the effect of Al2O3/PAG nanolubricant onto the power consumption. The study on the stability and characteristic of the Al2O3/PAG nanolubricant has been done prior the experiment. The result shows that the Al2O3/PAG nanolubricant is stable event after 28 days with concentration ratio above 70%. The highest power saving percentage of 23.89% is achieved when the AAC system is operated with 0.010% Al2O3/PAG nanolubricant. Further, it has been shown that the condenser pressure and evaporator pressure are correlated with the increment of the power consumption with average deviation of 3.129% and 2.919%, respectively. Finally, the power consumption of AAC system reduce with the usage of the Al2O3/PAG nanolubricant at low concentration.

Analysis on the monitoring system of energy conservation and comfort in office buildings based on internet of things

Abstract In order to reduce the cost of central air conditioning, we need to reduce its energy consumption. This paper briefly introduced Internet of Things and the energy-saving and comfort monitoring system of central air conditioning based on the Internet of Things. The system took comfort degree as constraint and energy efficiency as objective to control energy saving of central air conditioning. Company X in Guanghan, Sichuan, China, was taken as an example for analysis. The system was compared with the energy-saving control system which took temperature and power as constraints. Compared with before the energy-saving control, the proportion of air conditioning downtime in the working hours of employees increased after the implementation of the two kinds of energy-saving control systems, and the proportion of downtime under the energy-saving control system designed in this study was larger; in addition, after the control of the two kinds of energy-saving systems, the energy efficiency of the air conditioning significantly improved, and the air conditioning under the control of the energy-saving system proposed in this study had more improvement in energy efficiency and higher energy-saving efficiency. The energy-saving control method proposed in this study can effectively reduce the power consumption of the central air conditioning in the office.

Air conditioner consumption optimization in an office building considering user comfort

Rapid growth of energy consumption in last decades, made the world persuaded to energy optimization and management. Therefore, producers and prosumers should be equipped with the automation infrastructures to perform the management programs, like demand response. Office buildings are considering as a proper case for implementing energy consumption minimization since they are responsible for a huge portion of total energy consumption. This paper proposes a multi-period optimization algorithm implemented in Supervisory Control and Data Acquisition system of an office building. The developed optimization algorithm is an efficient solution considered for minimizing the power consumption of air conditioners by considering the user comfort constraints. A case study with several scenarios is implemented to verify the performance of proposed algorithm in real life using real data of the building. The obtained results show the impacts of different comfort constraints of algorithm while the main target of the optimization has been reached.