Air Conditioning Units Research Articles

Design of an Intelligent Purification and Disinfection Apparatus for Air Conditioning Units

With the sudden outbreak and rapid spread of COVID-19, global economic development and social stability have been seriously affected. The virus mainly spreads infection among people on a large scale through the air. People are gradually focusing on how to use HVAC system, so that it can play a more efficient and positive role in epidemic prevention and control. Consequently, we designed an intelligent purification and disinfection apparatus for air-conditioning units. The apparatus integrates rapid virus detection and high-efficiency disinfection functions. It uses a modular design and different operating modes for different levels of epidemic periods. This apparatus is not only suitable for daily life, but also can meet the prevention and control requirements during the epidemic period, which takes the economy, energy saving, and environmental protection into account.

Redevelopment of Huai Khwang Housing Project Responsive to Users’ Spatial Behaviors

Huai Khwang Housing is a public residential project, developed since 1972 in a fringe area of Bangkok at that time. The city has been gradually expanding, so now Huai Khwang Housing turns to be in the center of the city. There is a subway station 400 meters away from the site; therefore, the land value and potentials of this housing project has been increased. However, the physical conditions of the buildings are rather rundown since they have been utilizing for more than 50 years. The National Housing Authority of Thailand, the owner of this residence, has a plan to redevelop this housing project. The preliminary public hearing was set to inform the community about the future changes and intend to receive the opinions from the residents, who are elderlies residing in this community since it was built. Therefore, this paper aims to investigate the spatial behavior of elderly residents in this housing. The methods used include interviews and observations. The results show that the housing units are used in multi-functions and the spatial requirements include storage areas, a smell-locked and partitioning cooking area, a ventilating and sun-drying area for laundry, and spaces for air-conditioning units as well as satellite discs and washing machines. It is suggested that the redevelopment housing scheme should meet these requirements.

Performance of Air Conditioning Unit under Constant Outdoor Wet-Bulb Temperature and Varied Dry-Bulb Temperature

An experiment has been carried out for examining the performance of an air conditioning unit under constant outdoor wet-bulb temperature and varied dry-bulb temperature. During the experiment, the wet-bulb temperature of the compartment for outdoor unit was maintained at 22℃ and the dry-bulb temperature was varied from 24℃ to 36℃. The increase of outdoor air temperature results in the increase of supply air temperature, discharge temperature, suction temperature, and liquid line temperature. These cause the degradation of the air conditioner performance. An increase of power consumption by 1.4% and decrease of cooling capacity by 0.8% were observed for each 1℃ increase of outdoor air temperature. As a result, the energy efficiency ratio drops by 2% for each 1℃ increase of outdoor air temperature.

An Extensive Design Approach Integrating Offshore Residential Buildings and Solar Collectors

Utilization of energy has boosted socio-economic development but meanwhile exacerbated the environmental problems. Offshore areas in China boast abundant solar energy resources. The present work explores the application of solar energy in offshore residential buildings and the ways for integration of solar collectors with the buildings to analyze the potential impact of installation of solar collectors on the design of offshore residential buildings. An extensive design approach that introduces protruding features, outdoor air-conditioner unit spaces, and “virtual” elements into design of residential buildings was proposed, which would integrate the solar collectors into the architectural design and extend the functions of the residential buildings. This research aims to provide a theoretical basis for promoting utilization of solar energy and integrated design of offshore buildings.

Anaysis of Different Energy Efficiency Algorithms in Cloud Computing

Cloud computing is internet computing that offers metering-based services to customers. It implies accessing data from a consolidated pool of computer resources that may be requested and consumed on-demand. It also offers computer resources via virtualized over the internet. The data center is the most essential in cloud computing which includes a group of servers on which Business records are kept and applications operate. The data center which contains servers, cables, air conditioning units, networks, etc. uses more electricity and emits a large quantity of Carbon-di-oxide (CO2) to the atmosphere. One of the most significant problems encountered in cloud technology is the optimizing of Energy Usage. Hence the idea of cloud computing originated. It is a concept for allowing all over, on-demand access to a shared pool of customizable computer resources[ Wanneng Shu et. A.,2014].

Propagation of Mouth-Generated Aerosols in a Modularly Constructed Hospital Room

Modular construction methods have been widely used in the civil engineering industry due to ease of assembly, the convenience of design, and allowing for flexibility in placement while making the construction more sustainable. With the increasing number of COVID-19 cases, the capacity of the hospital is decreasing as more intensive care units (ICU) are allocated to COVID-19 cases. This limited capacity can be addressed by using modular construction to provide field hospitals. This paper adopts transient Lagrangian computational fluid dynamics simulations to investigate the importance of having an appropriate ventilation system in place to ensure sustainable infection control against airborne viruses and pathogens within a modular room. The performance of having a ventilation system using 10, 20, and 40 air changes per hour (ACH) was examined. In addition, different room configurations were also compared to provide useful guidelines for air conditioning units placement. It was determined that as the ACH rate increases while maintaining a direct flow field between the inlet and outlet, the rate of aerosol removal increases. Furthermore, the flowfield in which can be controlled by the placement of the inlet and outlet can impact the removal of aerosols, as it dictates how far the droplets travel before being removed from the enclosure.

Development of Eco-friendly & Self-Energizing Air-conditioner unit design.

Summer days are quite difficult to live in a non-ventilated house, thus most people choose for air conditioning or air coolers at home, which consumes electricity, money, and other resources. In this research paper, you will learn about the HVAC (Heat, Ventilation, and Air-conditioning) system, which is a revolutionary means of producing air conditioning by utilising natural resources such as wind and sunlight. The component required for this system is readily available. The maintenance is free, and it may be mounted on the roof of a house or elsewhere in the garden. Because the energy used in this system is freely available in nature, it is absolutely free and extremely efficient.

Complete Genome Sequence of Acinetobacter pittii BHS4, Isolated from Air-Conditioning Condensate in Hong Kong.

ABSTRACTAcinetobacter pittii is widespread in the environment, and the Acinetobacter calcoaceticus-baumannii complex, to which it belongs, is a major cause of hospital-acquired pneumonia and bacteremia. A. pitti BHS4 was isolated from an air-conditioning unit in Hong Kong and its complete genome sequence (3,901,980 bp; GC content, 38.79%) established through hybrid assembly.

Acoustic Sensing and Noise Identification of a Heating, Ventilation and Air Conditioning Unit: Industrial Case Study

Reducing the noise and improving the sound quality of vehicles’ interior space is one of the challenges to enhance passengers’ experience. This is an ever-growing issue as entirely electric cars are becoming commonplace, making previously unnoticed noise a significant problem. Heating, Ventilation and Air Conditioning (HVAC) units are a major noise source in a vehicle’s interior space, yet automotive manufacturers only give a maximum dB specification to HVAC unit manufactures. Problematic noise is only typically identified once the unit is within the vehicle at the late stages of a project. Psychoacoustics is the study of human perception to sound, allowing unpleasant noise to be identified within recorded data. Within this study, an industrial prototype HVAC unit was analysed using a 96-channel acoustic camera capable of isolating and locating noise sources from the unit using beamforming. In addition to identifying the location of noise sources, several psychoacoustic metrics were used, such as sharpness and loudness, to identify undesirable noise within an extensive data set due to the vast range of test configurations. Testing was conducted to analyse the unit. Within the initial testing, an ‘annoying’ sound was identified at a particular motor RPM, and this was located using the camera to an area which indicated that it was a result of structural resonance. In addition, present was a high-frequency source which could not be located accurately. The results of this testing enable modifications to the unit to be made early in its’ development, either structurally to alter the resonance of the unit or within the settings to ensure certain RPMs are avoided.

Improved energy balance calculation of unitary air conditioners via virtual in-situ calibration

Data-driven technologies for intelligent building energy management and automation have been developed under the energy balance state of systems. The datasets required are typically derived using energy and mass balance principles at each system boundary. Hence, the energy balance of systems significantly affects the system and building performances. However, sensor errors in a building energy sensor network can hinder the identification of balance states, thereby causing energy balance calculation errors in operational systems. In this study, the cooling capacity balance errors between the air and refrigerant sides of two unitary air-conditioner systems, caused by measurement errors, are investigated experimentally. Virtual in-situ sensor calibration (VIC) is performed to determine hidden sensor errors that cause the cooling capacity balance error, as well as to improve the balance and the degraded system performance analysis by calibrating the measurement errors. Experiments reveal the extent of cooling capacity balance errors occurring between the air and refrigerant sides under different operational conditions (0.5%–14.8%). VIC reveals erroneous measurements and the manner by which energy balance errors with measurement errors are solved (below 2%). Finally, the system performance analysis of the two test units shows that the VIC-driven calibration datasets improve the accuracy (0.3%–1.8% errors) of the system energy efficiency ratio even for new test cases after VIC is applied. The primary contributions of this study are as follows: (1) VIC is applied to solve energy balance calculation errors; (2) a strategy is proposed to overcome insufficient datasets to ensure energy balance improvements; and (3) calibrated measurements in real systems are validated.

Heat waves effect on daily mortality in districts in Madrid: The effect of sociodemographic factors

Abstract Background Although there is significant scientific evidence on the impact of heat waves, there are few studies that analyze the effects of sociodemographic factors on the impact of heat waves below the municipal level. Methods The objective of this study was to analyze the role of income level, percent of the population over age 65, existence of air conditioning units and hectares (Ha) of green zones in districts in Madrid, in the impact of heat on daily mortality between January 1, 2010 and December 31, 2013. Seventeen districts were analyzed, and Generalized Linear (GLM) Poisson Regression Models were used to calculate relative risks (RR) and attributable risks (RA) for the impact of heat waves on mortality due to natural causes (CIEX:A00-R99). The pattern of risks obtained was analyzed using GLM univariates and multivariates of the binomial family (link logit), introducing the socioeconomic and demographic variables mentioned above. Results The results indicate that heat wave had an impact in only three of the districts analyzed. In the univariate models, all of the variables were statistically significant, but Ha of green zones lost significance in the multivariate model. Income level, existence of air conditioning units, and percent of the population over age 65 in the district remained as variables that modulate the impact of heat wave on daily mortality in the municipality of Madrid. Income level was the key variable that explained this behavior. Conclusions The results obtained in this study show that there are factors below the municipal level (district level) that should be considered as focus areas for health policy in order to decrease the impact of heat and promote the process of adaptation to heat in the context of climate change. Key messages There are factors below the municipal level which should be considered for health policy in order to decrease health heat impacts. Privation hamper isolation of ageing people from extreme outdoor temperatures. Therefore, in some cases poverty could become the key risk factor that explain the vulnerability to heat waves.

Performance, environment, and cost‐benefit analysis of a split air conditioning unit usingHC‐290 andHCFC‐22

AbstractA widely used hydrochlorofluorocarbon (HCFC) refrigerant HCFC‐22 in the split air conditioner (AC) is being phased out in all countries under the Montreal Protocol. Propane (HC‐290) is a favorable substitute for HCFC‐22. The performance, environment impact and cost‐benefit analysis of a split AC unit operated with HCFC‐22 and HC‐290 has been carried out experimentally under different test conditions prescribed by IS 1391. The results showed that the variation in system performance was more significant for HCFC‐22 than for that of HC‐290 while varying the refrigerant charge. The experienced optimum charges that represent the maximum coefficient of performance (COP) was varied with the working environment and it was realized that, generally the optimum charge for HC‐290 was 50% lesser than that of HCFC‐22. The COP of the AC unit with HC‐290 was observed to be 5% more than that of HCFC‐22. However, the system capacity diminished by 7.8%. The operation of a split AC unit with HC‐290 produced up to 15.9% lesser CO2emission than that of HCFC‐22 under all the test conditions. The use of HC‐290 in an existing HCFC‐22 split AC system can save up to 12.22% of the life time total cost. Finally, it was inferred that the replacement of HCFC‐22 with HC‐290 in the split AC unit showed dominance in all aspects such as performance, emission, and life time total cost.

Association of mold levels in urban children’s homes with difficult-to-control asthma

Mold sensitization and exposure are associated with asthma severity, but the specific species that contribute to difficult-to-control (DTC) asthma are unknown. We sought to determine the association between overall and specific mold levels in the homes of urban children and DTC asthma. The Asthma Phenotypes in the Inner-City study recruited participants, aged 6 to 17 years, from 8 US cities and classified each participant as having either DTC asthma or easy-to-control (ETC) asthma on the basis of treatment step level. Dust samples had been collected in each participant's home (n= 485), and any dust remaining (n= 265 samples), after other analyses, was frozen at -20oC. The dust samples (n= 265) were analyzed using quantitative PCR to determine the concentrations of the 36 molds in the Environmental Relative Moldiness Index. Logistic regression was performed to discriminate specific mold content of dust from homes of children with DTC versus ETC asthma. Frozen-dust samples were available from 54% of homes of children with DTC (139 of 253) and ETC asthma (126 of 232). Only the average concentration of the mold Mucor was significantly (P< .001) greater in homes of children with DTC asthma. In homes with window air-conditioning units, the Mucor concentration contributed about a 22% increase (1.6 odds ratio; 95% CI, 1.2-2.2) in the ability to discriminate between cases of DTC and ETC asthma. Mucor levels in the homes of urban youth were a predictor of DTC asthma, and these higher Mucor levels were more likely in homes with a window air-conditioner.

Urgency of rapid Legionella detection post-COVID-19 lockdowns: an interview with Elizabeth Minogue.

Urgency of rapid Legionella detection post-COVID-19 lockdowns: an interview with Elizabeth Minogue.

Development of biomass based-activated carbon for adsorption dehumidification

Desiccant dehumidification systems can be utilized for decoupling moisture removal duty from the conventional mechanical vapor compression systems. Dehumidification using desiccant dehumidifiers is expected to exhibit a better energy efficiency. However, the high energy needed in the regeneration process limits its applicability. To realize the full potential of this technology, it is necessary to develop materials that can be regenerated using heat sources under 70 °C. In this study, activated carbons (ACs) derived from waste biomass were developed as desiccant materials. The ability of activated carbon (AC) to remove the moisture was controlled by carefully preparing the material to achieve the right operation window for optimum moisture sorption processes. The porous and surface characteristics of the newly-prepared AC were analyzed and compared with those of silica gel. The adsorption isotherm measurements were conducted, and the data were fitted with Henry–Sips and Do–Do isotherm models. The current ACs exhibit an excellent water adsorption capacity (up to 0.41 g/g). The efficacy of the ACs for dehumidification applications was assessed using the weather data from several regions of Indonesia, from North Sumatera to Papua. The results revealed that under the studied conditions, the new desiccant material showed a better dehumidification capacity than silica gel. Moreover, the reported AC can be regenerated using temperatures as low as 40 °C, which is readily available from waste heat, including the heat rejection from the condenser of an air-conditioning unit.

Deep Learning-Based Method for Detection of External Air Conditioner Units from Street View Images

Heat waves may negatively impact the economy and human life under global warming. The use of air conditioners can reduce the vulnerability of humans to heat wave disasters. However, air conditioner usage has been not clear until now. Traditional registration investigation methods are cumbersome and require expensive labor and time. This study used a Labelme image tagging tool and an available street view images database to firstly establish a monographic dataset to detect external air conditioner unit features and proposed two deep learning algorithms of Mask-RCNN and YOLOv5 to automatically retrieve air conditioners. The training dataset used street view images in the 2nd Ring Road area of downtown Beijing. The model evaluation mAP of Mask-RCNN and YOLOv5 reached 0.99 and 0.9428. In comparison, the performance of YOLOv5 was superior, which is attributed to the YOLOv5 model being better at detecting smaller target entities equipped with a lighter network structure and an enhanced feature extraction network. We demonstrated the feasibility of using street view images to retrieve air conditioners and showed their great potential to detect air conditioners in the future.

Effects of Simulated Adverse Environmental Conditions Related to Actual Conditions at Health Promoting Hospitals on the Performance of Blood Glucose Testing by Glucose Meters.

Annual peaks in temperature and humidity exceed manufacturers' specifications for blood glucose test strip storage in Thailand. Health Promoting Hospitals (HPH) do not always provide the same level of health services that hospitals do since they often only turn on air-conditioning units during working hours. The blood glucose testing performance of 4 glucose meters were investigated for short and long terms stress at 5 simulated conditions. Temperature and relative humidity (RH) at 5 HPHs in different regions of Thailand were monitored for 9 weeks during April to July 2019. The use of air conditioning in storage rooms for storing test strips was surveyed at 131 HPHs using questionnaires. Median-paired differences of glucose measurements with stressed test strips in 5 simulated conditions significantly differed (P < 0.05) both in the short term (3 days) and in the long term (30 days) with 4 glucose meters when compared to unstressed test strips. The average temperature of all HPHs exceeded 30°C (86°F). The average RH was 84%. There was only one HPH that occasionally turned on its air conditioners. Most HPHs kept both opened and unopened vials of test strips in rooms without air conditioners. Further, 21.4-32.0% of HPHs kept test strips at room with air conditioners. This study provides evidence for poor performance of blood glucose testing by glucose meters that are affected by adverse environmental conditions. The environmental for test strips storage at HPHs should be considered to prevent analytical errors of glucose measurement.

Comprehensive investigations on Life Cycle Climate Performance of unitary air-conditioners

Life Cycle Climate Performance (LCCP) evaluation of air conditioning systems helps to mitigate the carbon emissions from the rapidly expanding air conditioning systems. Nevertheless, different counties have different system evaluation standards, weather conditions, grid emission factors, and material carbon emission coefficients. Furthermore, new R-410A alternatives like R-466A were rarely discussed. Besides, some researchers used the weather station data instead of onsite weather data. However, the weather data collected from the UMDCP campus and the College Park airport in the USA were different up to 5 °C due to the heat island effect. This paper used a unitary air conditioner as a case study and compared the LCCP calculation results for 11 cities worldwide for five different refrigerants. As excellent candidates for replacing R-410A from the LCCP perspective, R-32, R-290, R-452B, and R-466A are considered in this study. Then, the results using field test data and weather station data were compared. In conclusion, annual energy consumption is a significant factor in high-emission-factor countries. In some low-emission-factor countries, the LCCP can be decreased by up to 60% by using R-290. The differences between the actual inlet air temperature to the outdoor unit and local weather station measured temperature can result in up to an 8% difference in LCCP. For future work, more works on futuristic assumptions for grid emission factors and variable speed systems are needed while considering the expansion of renewable energies and energy efficient variable speed systems.

Climatization and luminosity optimization of buildings using genetic algorithm, random forest, and regression models

With the rise in popularity of artificial intelligence, coupled with the growing concern over the environment, there has been a surge in the use of intelligent energy management systems. Additionally, as more buildings transition into the smart grid and, consequently, more energy and environmental data is gathered, there has been a significant increase in the number of data-driven approaches for building management systems. This paper proposes a methodology that aims to optimize the climatization and luminosity inside a building, using a genetic algorithm, a random forest, and two polynomial models. The proposed methodology enables the real-time management of the building taking into account the user needs and preferences. Air conditioner units and light systems are optimized to minimize energy costs, while also improving the air quality and considering the users’ temperature and luminosity preferences. This paper shows the results achieved, by the proposed solution, in an office building case study. The promising results demonstrate the possibility of minimizing energy costs while maximizing the users’ comfort.

Building condition assessment using artificial neural network and structural equations

Building facilities condition assessment is considered a fundamental aspect of an effective decision-making maintenance management plan to fulfill service requirements. A noticeable dearth of studies is believed to have delivered condition assessment approaches for existing buildings; however, these approaches are still deemed premature, with some limitations in demand enhancement. This paper presents a novel physical condition assessment framework for existing educational buildings that contribute to the body of knowledge by offering a state-of-the-art approach incorporating an Artificial Neural Network (ANN) predictive model and a Structural Equation Model (SEM). The ANN predictive model aims to forecast the future condition-rating states for each facility component in various building spaces. Simultaneously, the SEM determines the proportionate weights of building facilities components. The primary objectives of this paper are to prioritize building components for maintenance purposes and record the potential effects of several parameters influencing the condition state of building components. These objectives can be achieved via four sequential modules: 1) scan to BIM module; 2) condition assessment prediction module; 3) proportionate weight determination module; and 4) entire space rating value module. Condition-monitoring data on six different buildings' internal components are analyzed to anticipate their future condition. The components carried out are: 1) wooden flooring tiles; 2) gypsum board ceiling tiles; 3) wooden doors; 4) wooden windows, 5) split air conditioner units; and 6) desktop computers. The overall coefficient of determination (R2) of the developed ANN models for the predicted six components conditions are 0.99, 0.99, 0.927, 0.88, 0.97, and 0.972, respectively.