Air Conditioning Units Research Articles

Probabilistic neural network-based diagnosis of blockage faults in air conditioning and refrigeration units

Abstract The refrigeration unit is a core component of the air conditioner, and its typical faults are pipe scaling and blockage, which can cause refrigerant leakage in serious cases, and these faults can affect the cooling effect of the air conditioner and even affect the safety of using the air conditioner in serious cases. Therefore, it is necessary to study the fault diagnosis system of the refrigeration unit. The traditional fault diagnosis system for refrigeration units, which generally uses wireless sensor networks to transmit data, is a challenge because of its slow diagnosis speed and the low accuracy rate of fault diagnosis for refrigeration units. This paper uses a probabilistic neural network (PNN) to debug a blockage fault diagnosis algorithm system for simulated fault training. The system successfully achieves four levels of pre-warning for blockage faults: “uncertainty, micro-blockage, blockage, and severe blockage”, with the fastest pre-warning time of “uncertainty, micro-blockage” being less than 2 seconds. The experimental results of this paper show that the PNN system can take timely measures against blockage faults, and the fault diagnosis accuracy of the model reaches 97.97%, which is 13.34% higher than the traditional fault identification algorithm. The PNN model can pinpoint the blockage faults of the refrigeration unit, which enables the working state of the refrigeration unit to be continuously optimized, and the air conditioner to maintain energy-efficient operation. The fault simulation of the air conditioning refrigeration unit in automatic control mode verifies the blockage fault diagnosis’s accuracy and the algorithm’s feasibility, providing reference and learning for the development of fault diagnosis algorithms.

Experimental evaluation of a vapor compression cycle integrated with a phase change material storage tank based on two strategies

In this survey, the integration of a vapor compression cycle with a phase change material (PCM) storage tank has been evaluated experimentally during the hottest days of five cities with different weather conditions: Tehran, Ramsar Hamedan, Bushehr, and Ahvaz. The temperature conditions for outdoor (condenser, compressor, etc.) and indoor (evaporator) air conditioning units are provided with the help of two separated test chambers and a controller system. The desired system has been examined based on two scenarios. In each scenario, the system is assessed for the conventional air conditioning (AC) system (with no PCM involved) and the AC plus PCM unit. Based on scenario 1 operating strategy, the results indicate that adding the PCM tank decreases the total daily COP compared to the conventional AC unit, which varies from 32.07% for Bushehr city to 17.23% for Tehran city. Whereas the AC plus PCM system’s performance enhances during on-peak hours compared to the conventional AC system, which varies from 65.99% for Hamedan city to 12.84% for Bushehr city. Based on scenario 2 operating strategy, adding the PCM storage tank to the conventional AC unit increases total electric energy consumption over 24 h, which varies from 29.35% for Bushehr city to 5.49% for Tehran city. While it leads to shaving the electric peak load from 45.11% to 67.02% in which the highest peak load shaving belongs to Tehran and the least is related to Bushehr city.

Simulation and Optimization Study on the Performance of Fin-and-Tube Heat Exchanger

Heat exchangers (HX) are often utilized in industry, and the optimization of the performance of HX is a key area of research. In this study, EVAP-COND software 4.0 and genetic algorithm (GA) based optimization methods were proposed to optimize the circuitry and fin pitch of a finned tube heat exchanger for an air conditioner. A simulation model for a multi-circuit finned-tube evaporator used in an air conditioning unit was developed using the EVAP-COND software, and further validated based on the experimental data. Considering the refrigerant flow maldistribution of the original HX, four different circuit arrangements, i.e., types A, B, C, and D, were designed and optimized circuitry obtained. Based on both simulation and experimental results, D-type HX with 1.8 mm fin pitch was selected as 10% tubes could be saved with no significant loss of heat transfer capacity. Then the fin pitch was further optimized using the multi-objective GA method, with both Colburn factor j and friction factor f being considered. Optimization results showed that, in Pareto front, points 1 to 4 showed the increase in the Colburn factor j was negative, while the decrease in the friction factor f was positive. The friction factor decreased by 3.5% as one moved from Point 1 to Point 4, but the Colburn factor rose by 1.02%. Points 5 to 10 demonstrated that, while the decrease in the friction factor was negative, the increase in the Colburn factor was positive. The friction factor decreased by 5.31%, but the Colburn factor increased by 1.51% when going from Point 5 to Point 10. The results of optimization demonstrated that the objective function performed at its optimum when the fin pitch was around 1.77 mm.

Experimental verification of artificial neural network scalability for performance monitoring of multi-split type air conditioners

The scalability of a cost-effective and non-intrusive method for performance monitoring of multi-split type air conditioners is experimentally demonstrated on systems with different nominal capacities and design features. The method relies on an artificial neural network (ANN) technique, which uses easily measurable parameters representative of the refrigerant cycle and manipulated control parameters as the input for predicting the real-time cooling capacity of the system. Two air conditioning units intended for training and testing of the ANN model, are tested while being operated with their native control system in a broad range of experimental conditions for verifying the proposed methodology. The model scalability relies on the similarity of the fundamental working principles of vapor compression air conditioners. It is confirmed that temperature measurements in selected locations of the refrigerant pipeline and the total power consumption represents a suitable set of inputs for ensuring high prediction accuracy and ANN model scalability with rated system specifications from the product catalogue. The results show that the proposed monitoring method achieves accurate and generalizable predictions of the cooling capacity while limiting the relative error to below 10%.

Solar Powered Air-Conditioning Using Absorption Refrigeration Technique

The present work includes design, construction and operates of a prototype solar absorption refrigeration system, using methanol as a refrigerant to avoid any refrigerant that cause global warming and greenhouse effect. Flat plate collector was used because it’s easy, ninexpensive and efficient. Many test runs (more than 50) were carried out on the system from May to October, 2013; the main results were taken between the period of July 15, 2013 to August 15, 2013 to find the maximum C.O.P, cooling, temperature and pressure of the system. The system demonstrates a maximum generator temperature of 93.5 oC, on July 18, 2013 at 2:30 pm, and the average mean generator temperature Tgavr was 74.7 °C, for this period. The maximum pressure Pg obtained was 2.25 bar on July 19, 2013 at 2:00 pm. The current system shows cooling capacity of 0.15 ton with coefficient of performance of 0.48, and minimum evaporator temperature obtained was 14.2oC. A comparison of the present with previous works, showed that most of the previous work used ammonia as the main refrigerant, and even that used methanol it was as aqua methanol, or to be part of pair refrigerant, while the present work use the methanol as the main and the only refrigerant in the system. The results and the factors that provided by the current work, give a good understanding for using the methanol as a refrigerant with the solar absorption system. And the system can work in continuous operation cycle. This work gave fundamental understanding for designing solar refrigeration system, by using the results of present study to design air-conditioning unit, with one ton capacity, using the solar energy, and the methanol as a refrigerant.

Study on Preparation and Properties of PNIPAm/PPy Hydrogel Hygroscopic Material for Solid Dehumidification System

Air-conditioning systems account for 40–60% of the energy consumption of buildings, and most of this figure corresponds to the cooling and dehumidification process of air-conditioning units. Compared with traditional compressed air-conditioning systems, solid adsorption dehumidification systems possess good potential to improve indoor air quality and reduce buildings’ energy consumption. However, there are still some problems that prevent the use of solid adsorption dehumidification systems, such as their complexity and high regeneration temperatures. The key to solving the above problem is the discovery of more suitable adsorbents. In this paper, poly N-isopropylacrylamide/polypyrrole (PNIPAm/PPy) hydrogel was selected as the research object, and the performance of the dehumidification material and its potential for application in solid dehumidification systems were studied. It was found that the pore structure of PNIPAm/PPy was relatively complex and that there were abundant pores with uneven pore sizes. The minimum pore size was about 4 μm, while the maximum pore size was about 25 μm, and the pore sizes were mostly distributed between 8 and 20 μm. Abundant and dense pores ensure good hygroscopic and water-releasing properties of the resulting hydrogel. The PPy inside the hydrogel acts as both a hygroscopic and photothermal agent. In an environment with a relative humidity of 90%, 60%, and 50%, the hygroscopic efficiency of PNIPAm/PPy reached 80% in about 75, 100, and 120 min, and the corresponding unit equilibrium hygroscopic capacity values were 3.85 g/g, 3.72 g/g, and 3.71 g/g, respectively. In the initial stage, the moisture absorption increased with the increase in time; then, the increase in moisture absorption decreased. When the temperature was below 40 °C, the hygroscopic performance of PNIPAm/PPy was almost temperature-independent. The PNIPAm/PPy with different thicknesses showed similar moisture absorption efficiency. The lowest desorption temperature of PNIPAm/PPy was 40 °C, which indicates that low-grade energy can be used for material desorption. And the higher the temperature, the faster the desorption rate of PNIPAm/PPy and the higher the desorption amount. It can be seen that the PNIPAm/PPy hydrogel presents good desorption performance and can be used repeatedly.

Effect of Volute-Tongue Clearance on the Aerodynamic Performance and Noise of Multi-Wing Centrifugal Fan for Air Conditioning

Multi-wing centrifugal fans are wildly used in the central air-conditioning. The influence of dimensionless clearance of the volute-tongue on aerodynamic performance and noise is studied by numerical simulation and experimental tests in this paper. The complicated internal flow related to unsteady flow in a centrifugal fan with multiple wings is investigated by numerical simulation. Besides, the influence of circumstance on the noise is analyzed. It is testified that the internal flow of centrifugal fans is ameliorated using appropriate volute tongue clearance. Reduced eddy current decreased the local-flow loss near the volute tongue and exit. The experimental results show that the static pressure of model △t/R2=0.12 rose to 7.5 Pa and the aerodynamics noise value reduced to 4 dB compared with that of a reference model. Meanwhile, an obvious reduction of aerodynamics noise by 3.74 dB is obtained for model △t/R2=0.12 installed in the air conditioning unit. The static pressure of centrifugal fan is significantly improved for the model with a cochlear tongue clearance ratio of △t/R2=0.12. It is further demonstrated that the proper dimensionless distance effectively suppresses the aerodynamic noise of forward multi-wing fans.

DLSU Initiatives and Challenges: Energy & Climate Change

De La Salle University is committed to reducing its impact on the environment and to promoting positive action that will help reduce its carbon footprint. In its vision-mission, it emphasizes the need to be “attuned to a sustainable earth.” This paper presents the different initiatives and challenges faced by the university, especially while still in a global pandemic. A number of initiatives have been undertaken to promote energy efficiency in campus operations and climate action, particularly regarding reducing greenhouse gas emissions. However, facing the COVID-19 pandemic and preparing campus operations for the gradual resumption of face-to-face classes have presented new challenges moving into the next normal. The need to address health and safety concerns has resulted in increased consumption of electricity. Challenges are experienced particularly in ensuring improved indoor air quality as well as allowing indoor-outdoor air exchange. The setting up of (a) air purifiers and/or additional auxiliary fans in high foot-traffic areas, (b) installation of HEPA filters and UV-C lamps into HVAC systems, (c) extended use of air conditioning units to allow purging of air before and at the end of activities, and (d) the opening of air exchange dampers in the University’s HVAC systems, are all expected to result in increased demand for electricity.

Fine particulate matter infiltration at Western Montana residences during wildfire season

Background/aimsWildfire air pollution is a growing public health concern as wildfires increase in size, intensity, and duration in the United States. The public is often encouraged to stay indoors during wildfire smoke events to reduce exposure. However, there is limited information on how much wildfire smoke infiltrates indoors at residences and what household/behavioral characteristics contribute to higher infiltration. We assessed fine particulate matter (PM2.5) infiltration into Western Montana residences during wildfire season. MethodsWe measured continuous outdoor and indoor PM2.5 concentrations from July–October 2022 at 20 residences in Western Montana during wildfire season using low-cost PM2.5 sensors. We used paired outdoor/indoor PM2.5 data from each household to calculate infiltration efficiency (Finf; range 0–1; higher values indicate more outdoor PM2.5 infiltration to the indoor environment) using previously validated methods. Analyses were conducted for all households combined and for various household subgroups. ResultsMedian (25th percentile, 75th percentile) daily outdoor PM2.5 at the households was 3.7 μg/m3 (2.1, 7.1) during the entire study period and 29.0 μg/m3 (19.0, 49.4) during a 2-week period in September impacted by wildfire smoke. Median daily indoor PM2.5 at the households was 2.5 μg/m3 (1.3, 5.5) overall and 10.4 μg/m3 (5.6, 21.0) during the wildfire period. Overall Finf was 0.34 (95 % Confidence Interval [95%CI]: 0.33, 0.35) with lower values during the wildfire period (0.32; 95%CI: 0.28, 0.36) versus non-wildfire period (0.39; 95%CI: 0.37, 0.42). Indoor PM2.5 concentrations and Finf varied substantially across household subgroups such as household income, age of the home, presence of air conditioning units, and use of portable air cleaners. ConclusionsIndoor PM2.5 was substantially higher during wildfire-impacted periods versus the rest of the study. Indoor PM2.5 and Finf were highly variable across households. Our results highlight potentially modifiable behaviors and characteristics that can be used in targeted intervention strategies.

Evaluating Savings Potentials Using Energy Retrofitting Measures for a Residential Building in Jeddah, KSA

Residential buildings in the Kingdom of Saudi Arabia (KSA) contribute to nearly half of the overall electricity consumption in the building stock, highlighting their significant role in energy consumption. While an upgraded energy code has been established and enforced for new buildings, existing buildings continue to operate at the same level of energy consumption. Therefore, there is a need for further energy upgrades in existing buildings. This study evaluates the energy savings potential of various energy retrofitting measures for a case study in Jeddah, KSA. Data from previous studies and current practices were collected and analyzed. Different energy upgrade measures, such as windows replacement, wall insulation upgrade, roof insulation upgrade, and air conditioning unit replacement, were selected and evaluated using a digital simulation tool called Design-Builder. The simulation results were compared to understand the potential percentage of energy savings. The average annual energy consumption (AAEC) was used as the primary performance indicator to compare the energy savings among the scenarios. The results demonstrate significant reductions in energy consumption for the proposed scenarios. Furthermore, the study examined the significant impact of uncertainties, specifically, the infiltration rate and AC setback temperature, on AAEC. In conclusion, the proposed scenarios have the potential to achieve substantial energy savings, ranging from 25% to 66%, depending on the number of energy retrofitting interventions employed. The findings of this study can serve as a useful reference for similar energy retrofitting projects.

Integrating Smart Energy Management System with Internet of Things and Cloud Computing for Efficient Demand Side Management in Smart Grids

The increasing price of and demand for energy have prompted several organizations to develop intelligent strategies for energy tracking, control, and conservation. Demand side management is a critical strategy for averting substantial supply disruptions and improving energy efficiency. A vital part of demand side management is a smart energy management system that can aid in cutting expenditures while still satisfying energy needs; produce customers’ energy consumption patterns; and react to energy-saving algorithms and directives. The Internet of Things is an emerging technology that can be employed to effectively manage energy usage in industrial, commercial, and residential sectors in the smart environment. This paper presents a smart energy management system for smart environments that integrates the Energy Controller and IoT middleware module for efficient demand side management. Each device is connected to an energy controller, which is the inculcation of numerous sensors and actuators with an IoT object, collects the data of energy consumption from each smart device through various time-slots that are designed to optimize the energy consumption of air conditioning systems based on ambient temperature conditions and operational dynamics of buildings and then communicate it to a centralized middleware module (cloud server) for management, processing, and further analysis. Since air conditioning systems contribute more than 50% of the electricity consumption in Pakistan, for validation of the proposed system, the air conditioning units have been taken as a proof of concept. The presented approach offers several advantages over traditional controllers by leveraging real-time monitoring, advanced algorithms, and user-friendly interfaces. The evaluation process involves comparing electricity consumption before and after the installation of the SEMS. The proposed system is tested and implemented in four buildings. The results demonstrate significant energy savings ranging from 15% to 49% and highlight the significant benefits of the system. The smart energy management system offers real-time monitoring, better control over the air conditioning systems, cost savings, environmental benefits, and longer equipment life. The ultimate goal is to provide a practical solution for reducing energy consumption in buildings, which can contribute to sustainable and efficient use of energy resources and goes beyond simpler controllers to address the specific needs of energy management in buildings.

Thermodynamic Analysis of Air Conditioning System for a Passenger Vehicle with Suction Line Heat Exchanger Using HFO-1234yf

In this study, the experimental thermodynamic performance and environmental impacts of a vehicle air conditioner using HFO-1234yf with a suction line heat exchanger are studied and compared with HFC-134a results. The influences of air flow rate and air temperature at the evaporator inlet, condenser side air face velocity, and the compressor speeds on the thermodynamic performance of the system are investigated. The results showed that HFO-1234yf has a 12% improved coefficient of performance with 8% higher exergy efficiency than HFC-134a. However, HFO-1234yf has marginally poor performance at higher compressor speeds due to more irreversibilities occurred in the compressor and evaporator. The average SLHX effectiveness was observed to be 45% for HFC-134a, while it was 41% for HFO-1234yf. The HFO-1234yf has a 33.9% and 29.4% and 45.1% lower total equivalent warming impact than HFC-134a for petrol, diesel, and liquefied petroleum gas vehicles, respectively. This study paves a way to promote the use of HFO-1234yf instead of HFC-134a without major modifications in the vehicle air conditioner unit.

Performance assessment of fuel cell and electric vehicles taking into account the fuel cell degradation, battery lifetime, and heating, ventilation, and air conditioning system

In this study, fuel cell vehicles (FCVs) and electric vehicles (EVs) are considered for energy, i.e., hydrogen and electricity, consumption in varying working conditions, taking into account the heating, ventilation, and air conditioning (HVAC) unit. Since climate considerably influences vehicle performance, and cooling requires more energy than heating, a sweltering condition is studied. Added to this, New York City, a populous megacity, has been selected to dynamically evaluate the behavior of FCVs in real-world driving cycles. The findings suggest that the HVAC system can alter both the electricity consumption of EVs and the hydrogen consumption of FCVs in real-world driving cycles. In light of this, activating the air conditioning (AC) unit during a 10-min ride will cause a 33% energy consumption increase in EVs. This number reaches a significant 55% for the case of FCVs. The results also show that not only would a 20% reduction in battery state-of-health (SOH) consequently cause a 34.5% decrease in the driving range, but also the effect of battery health is more than that of the fuel cell. Moreover, passengers can lower the driving range by roughly 20% and 21.3% in EVs and FCVs, respectively.

Experimental evaluation of split air conditioning performance using nanodiamonds particles in compressor polyester lubricant oil

Rationing energy consumption in air conditioning (AC) systems has become increasingly necessary due to the continuous global increase in energy demand and the prevailing sustainability vision worldwide. Therefore, an AC system utilizing nanodiamond/Polyester (ND/POE) lubricant oil, which shows potential to improve the performance and reduce energy consumption, was investigated. Consequently, a 5-ton refrigeration split AC unit was modified with an oil separator to assess the ND/POE nanolubricant in the compressor’s loop, in particularly. The AC unit was examined under various operating conditions up to an extreme high ambient temperature of 52˚C, with an optimal nanolubricant concentration of 0.1% as recommended from the literature, using a fully automated psychrometric testing facility. The results showed that using ND/POE instead of pure POE resulted in a 4.7% and 3% reduction in compressor discharge temperature and pressure, respectively. Furthermore, the overall system's coefficient of performance (COP) improved by up to 8% due to a reduction in power consumption of up to 3% and an increase in cooling capacity of up to 6%. Therefore, it is anticipated that the use of ND/POE will result in improved compressor durability, reliability, and longevity, as well as a significant improvement in the performance of AC systems operating for prolonged periods, such as those operating in extreme high ambient temperature applications.

A solar powered off-grid air conditioning system with natural refrigerant for residential buildings: A theoretical and experimental evaluation

Residential air-conditioning units are essential for providing suitable interior comfort in regions experiencing hot climates. Nonetheless, these units contribute significantly to CO2 emissions in these countries due to their reliance on non-renewable energy sources and the use of environmentally unfriendly working fluids. This research aims to evaluate the feasibility of operating an off-grid solar-powered air-conditioning bed unit using low-GWP refrigerants that can efficiently replace conventional refrigerants. A model was developed to evaluate the vapour compression cycle's energetic and exergetic performance. Various refrigerants were employed as feeds to the mathematical model in order to simulate the unit's performance if environmentally friendly refrigerants supersede the conventional substances. An assembled prototype air-conditioning unit was built to provide cold air to a connected canopy. Two 400 W photovoltaic panels power this system, with battery storage providing electricity to the unit at night. TRNSYS was used to evaluate the batteries' energy storage capability, whilst Integrated Environmental Solutions Virtual Environment (IESVE) was used to estimate the amount of solar energy required to power the unit. On the basis of the energetic and exergetic findings, R290 and R600a have demonstrated their suitability as replacements for conventional refrigerants. In comparison to R134a, the system showed a 2.42% improvement in COP when using R290. This improvement was accompanied by a reduction in input work by 2.31% and an increase in exergetic efficiency by 2.37%. This paper provides a guideline for analytical design, combined with a coherent process system. This offers an excellent solution to the very real problems of major energy consumption in warm countries, combining a renewable energy source with an eco-friendly air-conditioning cycle.

Assessment of ventilation in low-resource healthcare settings: Montserrado County, Liberia—2022−2023

Background: Mitigating the risk of nosocomial respiratory disease transmission in the healthcare facilities of low- and middle−income countries (LMICs) poses unique challenges because mechanical ventilation and mixed−mode strategies are often unavailable. Carbon dioxide (CO2) can serve as a proxy for ventilation and, hence, airborne infectious disease transmission risk in naturally ventilated spaces. We assessed the adequacy of ventilation in Liberian hospitals. Methods: We sampled 3 hospitals, both urban and rural, in Montserrado County, Liberia. Moreover, 3 CO2 meters were concurrently utilized to measure CO2 levels at a 1-meter height in every patient-care room in each facility. We recorded temperature, humidity, room dimensions, and number of people in the rooms. From these variables, we calculated absolute ventilation using the ASHRAE equation to determine areas with the highest risk of nosocomial respiratory disease transmission. We also recorded qualitative observations about the sampled spaces. Results: From August 2022 to February 2023, 39 rooms in 3 healthcare facilities were sampled. Initial quantitative findings show that only 8 rooms (21%) met the WHO-recommended ventilation rate of 60 L per second per person. The average ventilation rate per person in the adequately ventilated settings was 86 L per second per patient, compared to 19 liters per second per patient in inadequately ventilated rooms. Additionally, 467 ppm mean CO2 was noted in well-ventilated rooms compared to 895 ppm mean CO2 in inadequately ventilated rooms.Initial qualitative observations showed that facilities with lower CO2 readings tended to be older constructions that likely had been constructed with airborne disease such as tuberculosis in mind. Willingness to open windows was limited by lack of window screens for malaria prevention, and there was a pervasive fallacy that air conditioning was a source of ventilation. Correspondingly, of the 31 inadequately ventilated rooms, 22 (71%) had operating air conditioning units compared with 4 (50%) of the 8 adequately ventilated rooms. Overall, of the 13 rooms without air conditioning, 7 (54%) were more frequently characterized by open windows compared to only 5 of 26 (28%) of rooms that did have air conditioners. Conclusions: Being prepared for the next respiratory disease outbreak and creating more resilient healthcare systems in LMICs requires a frameshift of prevention strategies. Measuring CO2 provides a simple strategy for identifying areas at highest risk for nosocomial respiratory disease transmission, which can be prioritized for low-cost environmental interventions, such as provision of window screens, as part of routine infection prevention and control efforts.Disclosure: None

Solar Air Conditioning System

Abstract: Rotary desiccant wheel are used to regulate the relative humidity of air streams. These are commonly integrated into heating ,ventilation and air conditioning unit to reduce the relative humidity of incoming ventilation air. Passive ventilation system are able to deliver adequate ventilation air but cannot control the humidity of the incoming air. To overcome this, the honeycomb water structure of rotary desiccant wheel was redesigned. In addition to this, the temperature of the regeneration air for desorption was lowered. Cooling pads were introduced in between the spokes of the wheel and filled with silica gel particles to form a rotary desiccant wheel. Computational fluid dynamics (CFD) model of the design was validated using experimental data.

A Novel PCM Cold Energy Storage System for Reducing the Power Consumption of Air-Conditioning Unit and Shifting the Daily Energy Peaks to Off-peak Hours

A Novel PCM Cold Energy Storage System for Reducing the Power Consumption of Air-Conditioning Unit and Shifting the Daily Energy Peaks to Off-peak Hours

Experimental investigation of influence of phase change materials in energy consumption of air-conditioning units and prediction performance evaluation of modified deep neural network model

In this study, the influence of hybrid phase change materials on the energy consumption of air-conditioning units installed to maintain a comfortable temperature inside the testing room was experimentally studied and numerically analyzed. The Paraffin, Halloysite and Ethylene glycol microcapsules were combined to form PHEg filler materials. These PHEg phase change materials were further mixed into a normal Portland cement mortar to prepare 5 different phase change material mortars. Based on the prepared motors, a pair of 1.22 m × 1.22 m × 0.2 m size test specimens were prepared to experiment. After testing the specimens with various outside temperatures, the energy consumed by an air-conditioning unit was reported. There was a 20–22% reduction in energy consumption recorded while testing with phase change material mortar specimens than normal cement mortar. Also, the results proved that the energy consumption of the air-conditioning unit could be reduced further by 10% when the outdoor temperature dropped to below 24 °C. In addition, the performances of prepared samples were predicted using a modified deep neural network model. The developed model accumulated 99.867% accuracy and a maximum of 0.1607 mean absolute error and 0.0172 root mean square error, better than several existing neural network models.

Grid Interactive Solar PV and Battery Operated Air Conditioning System: Energy Management and Power Quality Improvement

The drop in solar panel cost over past decade has accelerated the usage of solar photovoltaic (SPV) in various applications. In tropical countries, air conditioning unit is extensively used for cooling comfort. In this paper, PV generation is utilized with a battery energy storage (BES) for an air conditioner to reduce the impact of energy consumption from utility grid. Recently, air conditioning units are adopted with variable speed drive (VFD) that creates peaky nature of the input grid current due to the AC-DC conversion. The diode bridge rectifier (DBR) used for such conversion, does not allow bidirectional current flow. In this paper, considering such facts and taking the benefit of the VFD technology, an energy management methodology is proposed using PV array and BES to reduce the power consumption of air conditioning unit as well as it feeds excess PV generation to the grid with improved power quality. The DC power produced by the PV panel and BES is fed to DC bus of the VFD directly with the help of dual active bridge (DAB) converter, that eliminates DC-AC conversion stage. A voltage source converter (VSC) is interfaced as a front-end converter of VFD, to feed PV generation to the grid when air conditioner is not operating. This system is useful from multistory buildings to small consumers where the air conditioners are extensively used and PV array is installed. The concept of the system is validated by implementing in a prototype in the laboratory scale. The system is investigated with different possible scenarios. Under all test conditions, the THD of the grid current is found within the limits of the IEC 6100-3-2 standard.