Split Air Conditioner Research Articles

R152a-R13I1 mixture as an alternative to R1234yf for a mobile air conditioning: an estimation of flammability properties, thermodynamic and environmental performance

R152a-R13I1 mixture as an alternative to R1234yf for a mobile air conditioning: an estimation of flammability properties, thermodynamic and environmental performance

Numerical Investigation of Bionic Axial Fan used in Split Air Conditioner

Abstract: Bionic axial fan is the main component in the outdoor unit split type room air-conditioner (AC) which impact the cooling and comfort. The present work aims to improve the aerodynamic performances of bionic axial fan by numerical technique. The detailed simulation has been carried out to investigate the aerodynamic performance of bionic axial fan with various design proposals for a detailed investigation and development of a prospective fan design prior to the manufacture and testing of costly prototypes. According to the biological fact that the serrations at the wing improve the acoustics as well the aerodynamic performances, various design modifications performed on the bionic axial fan blade. As the serrations at the trailing edge help to improve the aerodynamic performance, the fan blade design modified to investigate the change in mass flow rate. The flow field is simulated with the finite element Computational Fluid Dynamics (CFD) solver Altair-AcuSolve to analyse the influence of trailing edge serrations on the air flow rate of fan. The three-dimensional (3D) computational domain with SpalartAllmaras (SA) turbulence model is considered to predict the air flow rate. The present computation is carried out for the axial fan speed of 820 rpm. The flow rate is correlated with the test results to validate the CFD modeling approach. The result shows that the trailing edge serrations at the tip of the fan has predicted improvement in flow rate since it alter the length of separation bubble near the trailing edge which also helps to reduce the noise level.

Research on the coordinate regulation behavior of window opening and split air conditioners usage during summer in mixed-cooling houses in hot-humid regions

In the hot-humid regions of South China, it is common for residents to utilize a combination of window opening and split air conditioners to cool their houses during summer. However, existing research focuses on investigating either window opening behavior or air conditioner usage behavior respectively, lacking a linkage study between these two approaches. Addressing this research gap, a novel coordinated regulation behavior model was developed by integrating both window opening and air conditioner usage behaviors. Due to different coordinate regulation modes, the tolerance temperature range in summer varies in mixed-cooling houses. Additionally, a degree of coordination is introduced to signify the level of overlap between window opening and air conditioner usage behaviors, indicating the uncertainty involved in choosing between these two actions. Moreover, residents exhibit a dynamic approach to switching between cooling methods, characterized by a transition range of approximately 2 °C rather than relying on a fixed temperature value. Notably, the simulated energy consumption results demonstrate a significant energy consumption disparity of up to 71 % among different behavior patterns. This study contributes to the academic understanding of the complex interactions between window opening and air conditioner usage and lays the foundation for achieving precise energy consumption simulation of mixed-cooling houses.

An experimental study on the effect of room setpoint temperature, and evaporator/condenser fouling on performance of a ductless split type air conditioner

Ductless splits can have several advantages over conventional systems including energy saving, improved thermal comfort, and performance. A deep understanding of the effect of changes in operating conditions of the unit is required to estimate the energy saving in the field. In this paper, a reference guide is created to classify the effects of different parameters on the performance of the ductless split unit. The experiments are categorized into three main topics: 1- The effect of setpoint temperature on the performance and energy consumption, 2- The effect of evaporator fouling on energy consumption, and 3- The effect of condenser fouling on energy consumption of a ductless split unit. Results show that one degree Celsius increment in room setpoint temperature reduces power consumption approximately 57 W and in annually energy consumption about 279 kWh. Furthermore, covering 30 % of the evaporator coil surface area and comparing with the normal case (evaporator coil with no coverage), parameters of Energy Efficiency Ratio, energy consumption, and cooling capacity drops 13.5 %, 6.4 % and 19.1 %, respectively. Likewise, by covering 1/3 of the condenser coil surface area and comparing with the normal case, Energy Efficiency Ratio, and cooling capacity drops 9.8 % and 2.4 %, respectively. The mentioned data indicate that the effect of the evaporator dirtiness on reducing the cooling load of the device is much higher than that of condenser.

A case study on optimizing industrial air conditioning with thermal solar energy in Egypt

This study investigates the feasibility of implementing a solar-assisted adsorption chiller in an industrial building at the Oriental Weavers International factory located in 10th of Ramadan City, Cairo, Egypt. The objective is to replace an inefficient split air conditioning system currently used to cool the Jacquard units during carpet manufacturing. The research begins by analyzing the performance of the existing cooling system to establish a baseline. It then explores the potential energy savings achievable by replacing the current system with a solar-assisted adsorption chiller. The existing oversized boiler will serve as an auxiliary heater for the new system. TRNSYS simulation tools are employed to model the building, simulate its thermal performance, and develop a solar-assisted cooling system. A parametric analysis investigates the impact of varying collector area and hot/cold-water storage tank volumes on key energy performance indicators. This analysis aims to determine the optimal component sizes needed for efficient system operation. Results indicate that a collector area of 90 m2 offers the optimal balance between performance and cost. There are minimal benefits to increasing the collector area beyond 100 m2. Larger hot water storage tanks demonstrate reduced outlet temperatures, reaching a maximum solar fraction at a capacity of 4 m³. The impact of cold-water storage tank volume on the system is minimal. The economic assessment reveals a payback period of 7.6 years, an Internal Rate of Return (IRR) of 14.3 %, and a Return on Investment (ROI) of 34.5 % over a 10-year period, indicating the financial viability of the proposed system. Furthermore, the solar-assisted adsorption chiller system has the potential for substantial environmental benefits. The system has the capacity to reduce CO2 emissions by up to 7200 metric tons. This highlights not only the technical feasibility of the system but also its economic and environmental advantages.

Corrective Evaluation of Response Capabilities of Flexible Demand-Side Resources Considering Communication Delay in Smart Grids

With the gradual increase in the proportion of new energy sources in the power grid, there is an urgent need for more flexible resources to participate in short-term regulation. The impact of communication network channel quality will continue to magnify, and factors such as communication latency may directly affect the efficiency and effectiveness of resource regulation. In this context of a large number of flexible demand-side resources accessing the grid, this article proposes a bidirectional channel delay measurement method based on MQTT (Message Queuing Telemetry Transport). It can effectively evaluate the real-time performance of communication links, considering that resources mainly access the grid through the public network. Subsequently, focusing on two typical types of resources on the demand side, namely, split air conditioners and central air conditioners, this article proposes an assessment method for correcting the response capabilities of air conditioning resources considering communication latency. Experimental simulations are conducted, and the results demonstrate that under given communication conditions, this method can more accurately estimate the response capability of air conditioners. This provides a basis for formulating more reasonable scheduling strategies, avoiding excessive or insufficient resource regulation caused by communication issues, and aiding the power grid in achieving precise scheduling.

Refrigerant Selection in Air Conditioning Systems Considering Thermodynamic, Environmental, and Economic Performance Using the BHARAT-II Multi-Attribute Decision-Making Method

A simple and effective multi-attribute decision-making method, named as "Best Holistic Adaptable Ranking of Attributes Technique (BHARAT)-II”, to choose the best refrigerant for air conditioning systems is presented. The thermodynamic properties of the refrigerants, and their environmental, and economic performances are also considered for the selection. Two case studies are provided to demonstrate the proposed multi-attribute decision-making method. The first case study addresses the problem of selecting the best refrigerant for residential split air conditioners out of 15 alternative refrigerants considering 12 selection attributes; the second case study addresses the problem of selecting the best refrigerant for automobile air conditioning systems by considering 14 alternative refrigerants and 13 selection attributes. The results of the proposed decision-making method are compared with those of other well-known multi-attribute decision-making methods such as EDAS, TOPSIS, and MOORA. The proposed method is shown to be simple to implement, providing a logical way for allocating weights to the selection attributes and is useful to solve the best alternative refrigerant selection problems of the residential as well as industrial refrigeration and air conditioning.

Heavy metals and microbial assessment of air conditioning condensate water in Jeddah city-Saudi Arabia: concept of sustainable water resources

The demand for water is rising worldwide, especially in Saudi Arabia, where the existing water sources are barely sufficient to meet the present requirements. Condensates from air-conditioning units can be invested as an economical and supportive source of available water resources, which can be considered within global water supply accounts. The aim of the present study is to examine the possibility of recovering condensate water from air conditioner (AC) systems by determining the quantity and quality of AC water generated by either split or window AC systems. The results showed that split air conditioner systems were more effective than window-type air conditioners in generating condensate water in terms of quantity and quality. There was a significant correlation between the humidity and water content. The results indicate that the annual amount of water generated was 8,725 L for window AC and 20,614 L for split AC. The recorded levels of all elements in the water samples obtained from both the window and split air conditioning units, including pH, TDS, EC, PO4-3, Cl-, SO4-2, COD, and heavy metals, were found to be within the acceptable thresholds set for both drinking water and irrigation purposes. Bacteria were only present in three water samples from the window AC, and all were non-pathogenic. Utilizing air conditioner condensate as a strategic measure can address the issue of water scarcity in Saudi Arabia’s agricultural and industrial sectors. The findings of this study are extremely relevant and opportune, especially given the growing concerns about water scarcity and the need to conserve resources. By demonstrating that the HVAC water condensate is clean and safe for consumption, this study adds to our understanding of how we can make better use of available resources.

DECREASING ELECTRICAL ENERGY COST AND INDIRECT CO2 EMISSIONS OF AN AIR CONDITIONING UNIT AFTER PREVENTIVE MAINTENANCE

During the summer season in subtropical countries and the dry season in tropical countries, air temperature is high. To adapt this condition, an air conditioning (AC) unit is used. The air conditioning use, however, increases the electrical energy consumption which contributes to the increase of indirect CO2 emissions. For many buildings, a monthly electrical energy cost from the use of AC system can contribute up to 40% of a monthly utility expenditure. It is then a great motivation to decrease electrical energy consumption of the AC unit. In this work, an adaptable preventive maintenance for an AC unit shows an acceptable level of electrical energy decrease. An experiment was performed for 2 AC types. The first one is a wall mounted unit with a cooling capacity of 9,300 BTUH. The second unit is a split duct unit with a cooling capacity of 48,000 BTUH. The cleaning of evaporator in the wall-mounted AC unit decreased the hourly electrical energy consumption by 4.1% from 810 to 777 Watt-hour. In addition, cleaning of condenser for the similar AC unit decreased the electrical energy consumption by 6.2% from 810 to 760 Watt-hour. Meanwhile, the evaporator cleaning for a 48,000 split duct AC decreased the hourly electrical energy consumption by 2.4% from 4.64 to 4.53 kWh and cleaning of condenser decreased the energy consumption by 5.4% from 4.64 to 4.39 kWh. If this electrical energy decrease could be scaled up to the global energy consumption from the air conditioning use, this should be a significant decrease of the global energy consumption and the correlated indirect CO2 emissions from the air conditioning sector.

ინოვაციური კონსტრუქციის მობილური კონდიციონერი

Mobile air conditioner is a portable device that is used to cool the air in rooms where it is not possible to install an air conditioner. It can be used in apartments, offices, hotel rooms, camps and other places. The basic principle of operation of mobile air conditioner is to take air from the air-conditioned room through the built-in fan, then the air passes through the filters and is cooled or heated in the built-in evaporator. The processed air is supplied back to the room through a flexible duct. One of the main advantages of mobile air conditioner is its portability. It can be easily moved from one room to another, and such air conditioner can also be taken to any address. Mobile air conditioner does not require complex installation and can be connected to a regular mains electricity supply. In addition, some mobile air conditioners may have a heating function during the cold season. However, mobile air conditioner has some disadvantages. It is usually not as efficient as air conditioner that requires installation (such as split type air conditioners), especially, in large rooms. It can also be noisy and take huge space in a room. It consumes more energy than built-in air conditioners, which can lead to higher electricity bills.

Heating and cooling challenges for electric vehicles: A comprehensive experimental study

An efficient mobile air conditioning (MAC) system using a safe and climate-friendly refrigerant is necessary for human comfort, increasing the vehicle’s energy performance, and reducing the fuel/electricity consumption. In the current work, we perform a drop-in experimental comparison for low GWP alternatives to R134a in reversible MAC systems. The study compares two lower global warming potential (GWP) refrigerants; R456A, a non-flammable refrigerant for R134a direct MAC replacement, and R1234yf, an ultra-low GWP and mildly flammable refrigerant that is the standard for new MAC systems. The system’s operational and energy performance is investigated, simulating a wide range of indoor and outdoor steady-state conditions. The measurements are recorded operating a fully monitored vapour compression test rig that uses secondary circuits to set the target conditions. In the heating mode (heat pump), the evaporation temperatures are set at −10 °C, −5 °C, and 0 °C, and condensation temperatures at 40 °C, 50 °C, and 60 °C. In cooling mode (air conditioning), the condensation temperatures are 37.5 °C, 45 °C, and 52.5 °C and are combined with evaporation temperatures of −7.5 °C, 0 °C, and 7.5 °C. In the heating mode, R456A presented a competitive COP to R134a with a reduction of less than 5 %, more remarkable at lower evaporation temperatures. In the cooling mode, R456A showed the lowest COP at a low condensation temperature. R456A and R1234yf COP are comparable at a higher condensation temperature, which suits the T3 climate conditions.

Comparative analysis of energy efficiency for three heating and cooling supply schemes in a region with hot summers and cold winters in a chemical industrial park

Building energy consumption in China accounts for 45% of the total national energy consumption, with air conditioning energy consumption representing approximately two-thirds of that. Therefore, energy efficiency in buildings is of utmost importance. This study focuses on a chemical industrial park located along the Fujiang River and compares three heating and cooling supply schemes: the river water source heat pump system, which utilizes river water as the heat source and heat sink; the water cooling unit and boiler system, which uses water-cooled electric compression chillers for cooling and an oil-fired boiler system for heating; and the split air conditioning and gas water heater scheme, which relies on refrigerants such as fluorine-containing compounds for cooling and a gas water heater for heating. By calculating the energy consumption of the above three schemes and conducting a comparative analysis, it is found that the river water source heat pump system exhibits significantly higher energy efficiency throughout the year compared to the water cooling unit and boiler system and the split air conditioning and gas water heater scheme. This highlights the notable energy efficiency advantage of the river water source heat pump system.

Experimental and Theoretical Assessment of Inverter-Operated Split Air Conditioner with Low GWP Alternative Refrigerants

This article presents experimental evaluation and comparative analysis of low GWP alternative refrigerants, namely HC-290 (propane), HC-1270 (propylene), HC/HC-1270 blend, and HFC-32 (difluoro methane) as drop-in replacements for HCFC-22 (Chloro difluoro methane) in a typical 1.5 TR capacity inverter operated split type air conditioner (SAC). The experimental setup consisted of retrofitting an original HCFC-22 test unit following the soft optimization of the SAC system for each alternative refrigerant, followed by testing under controlled operating conditions as per the IS 1391, Part-1 standard at the half capacity and the rated capacity of inverter SAC. The results obtained were compared against the baseline HCFC-22 test unit. The optimized SAC gave EERIS (Indian Seasonal Energy Efficiency Ratio) of 4.63 for HC-290, 4.71 for HC-1270 and 4.87 for HC-290/HC-1270 blend, respectively increased by 8.94 %, 10.82 % and 14.58 % compared to HCFC-22. HFC-32 delivered the maximum cooling capacity of 6.78 kW, 3.67 % higher than baseline unit at the rated capacity. HC-290/HC-1270 blend exhibited the lowest power consumption and discharge temperature amongst all the refrigerants considered. The charge of flammable refrigerants has been optimized below LFL satisfying EN378 standard for the safety of inverter SAC in domestic applications.

Experimental study of an on-grid hybrid solar air conditioner with evaporative pre-cooling of condenser inlet air

This paper presents an experimental study of a split type solar air conditioning system with evaporative pre-cooling at the condenser. The main objective of this research is to evaluate the thermal and electrical performance of the system under hot summer conditions in a Mediterranean climate. Previous studies have separately shown the benefits of both condenser inlet air pre-cooling and photovoltaic solar cooling. The novelty of this work will be the study of the coupling of these two techniques in a real installation, where the viability of the system depends on the component-level design and the operating conditions, since weather variables such as ambient temperature, relative humidity and solar radiation significantly affect the thermal behaviour of the refrigeration cycle, the evaporative pre-cooling capacity and the performance of the photovoltaic panels. Experimental tests were carried out over a summer season to evaluate the behaviour of the system and to obtain performance correlations validated with experimental data. These correlations will allow the modelling of the system and will be used to carry out an economic and environmental feasibility study of the proposed hybrid solar air conditioning system. The results show that a 100mm-thick evaporative pad achieved an average evaporative cooling efficiency for all tests performed of ɛevap=67.4%, reducing the air inlet temperature to the condenser by around 6°C. This resulted in an 18.3% improvement in the EER of the air conditioner. In addition, the use of evaporative pre-cooling resulted in a significant 23% reduction in peak power consumption. The study also evaluated the impact of the air pressure drop caused by the evaporative pad when not in use, with results favouring its installation. The system achieved a solar contribution of more than 30% under different solar radiation conditions when using pre-cooling, compared to 25% with a standard condenser. In addition, the combination of photovoltaic contribution and evaporative pre-cooling reduced energy consumption by 43%.

Grey-box modeling for thermal dynamics of buildings under the presence of unmeasured internal heat gains

An accurate grey-box building thermal model is an essential component for prediction-based control of split air conditioners. As the thermal performance of building envelope improves, the internal heat gains play an increasingly noteworthy influence on the building’s thermal dynamics. However, the internal heat gains are usually not measured, which makes the conventional data-dependent identification methods of building thermal models fail. To improve the accuracy of building thermal models under unmeasured internal heat gains, a two-step parameter identification framework for resistance–capacitance (RC) models is proposed in this paper. First, the time-invariant building model parameters are estimated by designing a novel optimization objective function. Next, the time-varying internal heat gains are identified based on the mismatch in predictions of the estimated building model from the first step and the measured temperature. The effectiveness of the method is evaluated using data from a simulation case and an experiment case. The results show that the proposed method outperforms the conventional identification method as well as two other identification methods that handle the unmeasured internal heat gains. Besides, the internal heat gains estimated by the proposed method can capture the trend of the actual internal loads well.

Real-time thermodynamic monitoring of split inverter ACs: amicrocontroller-driven investigation of performance

Recent technological advancements, particularly in air conditioning cooling systems, have led to rapid developments such as inverter technology. Inverter technology provides various advantages including energy savings compared to non-inverter air conditioners. Globally, the inverter modulates the compressor to continue operation despite reaching the set temperature. This study aimed to monitor the performance of split inverter air conditioners utilizing microcontroller technology. The microcontroller model employed was the ATmega2560, capable of logging each test parameter and displaying in real-time. Additionally, the ATmega2560 integrated sensors including the DS18B20 temperature sensor and PZEM 004-T multifunction electrical sensor. Monitoring occurred over one hour of operation on a 8525 Btu/h capacity split inverter AC. Experimental monitoring results showed the lowest Tsupply at T1 compared to other temperatures, reaching 8°C. At Treturn, both T1 and T2 exhibited identical decreasing trends to 25.5°C around 3000 s. The minimum power variation occurred at P5 relative to other variations. The average power consumption of the split inverter AC was approximately 750 W. The minimum energy consumption observed was at E5 during the study, while the maximum was at E1 with peak energy consumption of 0.96 kWh. Microcontroller-based experimental monitoring can provide real-time results and shows promise for monitoring split inverter AC performance.

The effect of refrigerant filling pressure on split AC performance with variations in refrigerant R22, R134A, and R290

R-22 refrigerant has been recognized as a major cause of climate change and ozone layer depletion, leading to increased interest in finding more environmentally friendly alternatives. Two alternatives being considered are R-134a and R-290. The main objective of this research is to compare the Coefficient of Performance (CoP) performance of split ACs using three types of refrigerants, namely R-22, R-134a, and R-290, taking into account the environmental impact and operational efficiency. The research method involved retrofitting a 1 PK split AC which initially used R-22 with three different types of refrigerant as an experiment. The research process includes test equipment design, equipment installation, and feasibility testing before carrying out experimental testing. Tests were carried out with variations in refrigerant charging pressure of 70 psi, 75 psi, 80 psi, 85 psi, and 90 psi. The research results showed that the largest COP was found in the R-290 refrigerant, reaching a value of 0.86 at a filling pressure of 90 Psi. The largest COP value for R-22 was also found at a filling pressure of 90 psi, namely 0.66. Meanwhile, R-134a achieved the highest COP value at a filling pressure of 90 psi, with a value of 0.57 at a variation of refrigerant filling pressure of 90 Psi. In conclusion, this study provides better insight into the efficiency and environmental impact of the three types of refrigerants discussed. It also provides a useful information basis for the selection of suitable refrigerants in split air conditioning systems, with the aim of environmental conservation and achieving optimal performance

Indoor space risk assessment based on Co-analysis strategy in split room air conditioning

The use of environmentally friendly hydrocarbon refrigerants in air conditioning systems is being promoted worldwide as a proactive measure to combat global warming and ozone depletion. A comprehensive analysis of hydrocarbon refrigerant leakage and the resulting fire risk is essential for split room air conditioning (SRAC) systems. The study presents a novel Co-analysis strategy that integrates the operation of SRAC systems with the assessment of indoor space fire risk. Experiments involving the leakage and diffusion of R-290 in SRAC system have been conducted to substantiate the validity of the Co-analysis strategy. This model is used to analyze the dynamic parameters of leakage and distribution patterns of hazardous areas within the SRAC indoor unit. The study considers various leakage hole sizes (1 mm, 2 mm, 3 mm) under both cooling and heating operating modes. The results show the leaking refrigerant flow rate presents different attenuation types under cooling and heating modes. When the leakage hole diameter is less than 2 mm in the cooling mode, the concentration of R-290 in the space is below 50 % lower flammable limit. The comprehensive fire risk probability of the R-290 indoor unit is 1.0 × 10−11∼5.0 × 10−10 for the cooling model and 1.0 × 10−11∼9.0 × 10−10 for the heating model. Effective methodologies for mitigating risks and optimizing the system are also proposed. Based on the Co-analysis strategy, this study presents a scientifically grounded assessment of the fire risk associated with air conditioning uses flammable refrigerants inside buildings. The strategy aims to enhance building safety.

Performance of Split Air Conditioner with Capillary Pipe Variations with R32 Refrigerant on Ships

Performance of Split Air Conditioner with Capillary Pipe Variations with R32 Refrigerant on Ships

Analysis of preferences of households for choosing heating and cooling systems: A discrete choice analysis in Iran

The residential sector uses a large fraction of energy for heating and cooling to provide comfort conditions for households. Technical features of appliances are determining factors of the demand for energy. The present paper thus aims to study the determinants of household adoption decision by applying the discrete choice model. Households face with unordered choice, and multinomial and mixed logit models are employed to study the heterogeneity of choices of households related to heating and cooling technologies. While most of the research works have considered preferences based on cross-sectional data collected through discrete choice experiments, the present study employs micro-level household survey data including observed preferences in order to contribute to better understanding of the actual choice behavior of households. In addition, the dynamic effect of variation of variables on the household preferences have been investigated over time. The results show that heterogenous preferences of families in choosing appliances are affected by socio-demographic characteristics. Analysis of marginal effects indicate that urbanization, education, building type and households expenditure are the most effective parameters. The level of education has the most positive impact on the adoption of wall-mounted package and split air conditioner where the probability of using them has increased by 1.65% and 4.87%, respectively. On the other hand, high education level reduces the probability of gas heater and fan adoption by 3.49% and 3.43%. The estimated results show that urbanization increases the probability of choosing central heating by 3.73% and split air conditioner by 6.1% while it decreases the adoption probability of oil heater by 5.02% and fan as by 8.9%.