Refrigerant In Air Conditioners Research Articles

Hybrid system development and application research for refrigerant leak inspection

Recently, record-breaking heatwaves due to global warming and abnormal weather have occurred in the summer, and sales and usage of air conditioners are rapidly increasing. Air conditioners are widely used all over the world and are recently expanding to centralized management system air conditioners. There are many customers requesting repairs due to leaking air conditioner refrigerant. However, the problem of refrigerant leakage is difficult to repair because it is difficult to quickly and accurately determine whether there is leakage on site. Air conditioner refrigerant leakage occurs in various parts such as outdoor units, indoor units, and connecting pipes, and there are cases of leakage due to minute defects, making it difficult to clearly determine whether there is leakage. Research was conducted to develop a hybrid system so that immediate judgment on these issues could be made in the field. A refrigerant leak diagnosis method was studied based on an acoustic emission sensor, and a refrigerant leak diagnosis procedure and hybrid diagnosis system were developed to detect refrigerant leak signals for each air conditioner component in consideration of the characteristics of the UV gas detector and each inspection method. It is expected that field diagnosis of air conditioning systems can be effectively applied using the procedure and diagnosis system developed through this study

Predicting the Refrigerant Amounts Across Air Conditioners With a Domain Adaptive Lightweight Transformer

Air conditioner consumers expect their products to work well without any problem. Consumers encounter problems if the amount of refrigerant in the air conditioner is insufficient. Therefore, we propose a novel deep learning approach that predicts the amount of refrigerant in advance. Our approach differs from others, as it is not limited to specific types of air conditioners and is applicable to all types. We propose a domain adaptive Transformer (DAT) that determines the amount of refrigerant using a Transformer encoder and domain adversarial training of neural networks. The proposed DAT reduces the model parameters by using a modified lightweight Transformer encoder and adds a domain classifier to build a universal model that is not limited to a specific type of air conditioner. We conduct the experiments by collecting data on the amount of refrigerant operating in the real fields. As a result, the proposed DAT achieves higher prediction performance. It is also significant that the results predicted by DAT are more accurate than those predicted by experts dealing with air conditioner refrigerant problems. As a result, DAT-based air conditioners are commercialized in real life. Hence, consumers can prevent the shortage of refrigerant without experts.

A novel thermal management system with a heat-peak regulator for fuel cell vehicles

Thermal management of fuel cell vehicles is posing a constant challenge due to the growing installed power of the fuel cell stack and consequent heat-overloaded situations of the radiator. Based on the “time-dependent” idea that considers the fluctuated heat generation and the intermittent heat peak during the journey, a novel thermal management system that employs a heat-peak regulator is proposed in the present work. The heat-peak regulator is a thermal accumulator filled with phase-change material that separately exchanges heat with the fuel cell coolant and the air conditioner refrigerant. It temporarily receives the excess heat that cannot be released out by the radiator when the heat peak occurs; later on, when the heat peak is gone, the heat is transferred to the refrigerant to remove it from the condenser. The system simulations based on the developed thermal models demonstrate that, the thermal runaway of the fuel cell stack can be eliminated or effectively weakened by this novel thermal management system, relying on the amount of the phase-change material filling the heat-peak regulator. In the present study, the 135 s and 250 s thermal runaway durations can be shortened to 0 s and 105 s, respectively, in the standardized New European Driving Cycle and World-wide Harmonized Light Duty Test Cycle under 38 °C summer weather, and the maximum temperature for the latter can be reduced from 89 °C to 83 °C. This work can make a significant contribution towards the solution of thermal management problems of the fuel cell vehicles.

Design And Development Of Air Conditioner (AC) Monitoring And Management System

Nowadays Air Conditioner (AC) has become a more important appliance in our life. Gas leakage, blockage in the evaporator and compressor coil, pipelines as well as dust in the air filters, are the major reasons behind AC explosion. Many people have been injured over the years due to AC blasts. In this paper a system is developed that uses sensor technology and smart devices to reduce AC blast. As a result, pipeline leaks or blockage fault detection system is planned and constructed using MQ-02, TTC 103, optical dust sensors for gas detection, temperature detection and for detecting dust density respectively. Also bacteria can be detected through MQ-3 gas sensor as it combines with AC refrigerant and produces ethanol. This system is also digitally connected to smart devices (cellphones) and a control device (RM MINI 3) so that user can receive a detection notification at any time and operate AC from any location. By implementing these sensors, the initial target was achieved. The work is low cost and environment friendly.
 
 Index Terms— Explosions, blockage, leakage, RM MINI 3, cellphone, refrigeration cycle, sensor, safety

Refrigerant alternative and optimization under the constraint of the greenhouse gas emissions reduction target

Fluorinated gases are considered greenhouse gases and have a global warming effect up to 22,800 times greater than that of carbon dioxide. Fluorinated gases are widely used as room air conditioner refrigerants. In view of the current lack of well-equipped refrigerant replacement technology and research on comprehensive and systematic refrigerant alternative schemes, we propose a decision-making method system for optimizing room air conditioner refrigerant alternative schemes suitable for meeting future greenhouse gases emissions reduction target constraints by integrating the life cycle assessment method, the system dynamics method and the multi-objective programming method. In accordance with the requirements of the Montreal Protocol and other relevant fluorine-containing substance elimination plans, four scenarios for refrigerant alternative schemes were designed, which include Business as usual scenario, Convention Scenario, Design Scenario and Ideal Scenario, respectively. The Convention Scenario is based on the refrigerant phase-out plan stipulated by international conventions in China; the Ideal Scenario is based on the use of refrigerants with minimal environmental impact within the range of available predictable technologies; and the Design Scenario is designed according to the degree of strictness between the Convention Scenario and the Ideal Scenario and used to propose more reasonable and feasible refrigerant use planning schemes. The results show that the ozone depletion ability of refrigerants will be eliminated with the phase-out of hydrochlorofluorocarbon refrigerant HCFC-22. The total cost of refrigerant substitution work under different alternative scenarios will cost a total of $1.378 billion to $1.672 billion, which is worthwhile considering the considerable environmental benefits. The refrigerant dosage scheme under design scenario II, which is 50% faster than the conventional phase-out scheme, is the optimal scheme for future refrigerant replacement phase-out in the room air conditioner industry. Under this scenario, the total economic cost is $1.672 billion; additionally, compared with those under the business as usual scenario, the greenhouse effect intensity will decrease by 78.2%, the safety risk will decrease by 6.8%, the energy consumption will decrease by 60.4% and the ozone depletion ability will decrease by 99.8%.

Classification of Refrigerant Flow Noise of Air Conditioners Based on Continuous Wavelet Transform and Support Vector Machine

This study proposes a classification method that uses the continuous wavelet transform and the support vector machine approach to classify refrigerant flow noises generated in an air conditioner. The air conditioning noise was identified as an abnormal signal by the use of the first- and second-order moments. The start and end times of refrigerant flow noises were identified by detecting the singularities of the continuous wavelet transform coefficient in the time domain and by means of listening to the measured sounds. Further, the time-frequency characteristics of refrigerant flow noise were analyzed with the continuous wavelet transform. For the support vector machine-based classification of refrigerant flow noise in an air conditioner, the grid search method was used to determine kernel hyperparameters. Five-fold cross validation was employed for the application of the support vector machine to the classification of air conditioner refrigerant noise. In addition, measured sound sources were modified based on classified refrigerant flow noise to compare the classification accuracy of a jury test with the results of the support vector machine.

A novel prototype of integrated anaerobic filter-condenser (ANCO) system for application of waste heat from office building to improve performances of both air conditioner and wastewater treatment system

The prototype system of integrated anaerobic filter with condenser of air conditioner (anaerobic filter-condenser; ANCO) was developed for sustainable water-energy management model in green office building. The ANCO consists of an insulated anaerobic filter (IAF) and condenser that are connected to an existing refrigerant of air conditioner. The system applied waste heat energy from an air conditioner to improve wastewater treatment efficiency. While the performance of air conditioner also could be enhanced by decreasing refrigerant temperature from transferring waste heat through the IAF system for increasing wastewater temperature. The waste heat from air conditioner could stimulate higher microbial activity in the IAF and at the same time, this could increase air conditioner performance. From the overall results, it was found that with wastewater flow rate 180 liter/day, the ANCO prototype could recycle waste heat approximately 2.82 kWh/day. The waste heat transferred into wastewater could increase water temperature up to averagely 35.4 °C. The system performance for removal of suspended solids (SS) and COD were averagely 49.9% and 49.3%, respectively. The coefficient of performance (COPOverall) of air conditioner was increased by 30.25% and electric consumption was decreased by 22.96%. The ANCO system could save electrical energy averagely 2.62 kWh/day. Then, the ANCO system can decrease heat into environment and decrease greenhouse gas emission 602 kgCO2eq/year. Therefore, the ANCO system was pronounced to be the prototype eco-friendly onsite-wastewater treatment system for green office building application.

Determination of effective parameters for diagnosis and classification of air-conditioning refrigerant noise by logistic regression

In the present study, refrigerant noise generated from an air-conditioning unit in operation was characterized as water or gas sounds by jury testing and was diagnosed and classified by logistic regression performed with objective sound quality parameters. A c2 test was conducted to determine the parameters that influenced the probability for refrigerant noise to occur. Furthermore, the probability of refrigerant noise occurring is determined, based on objective sound quality parameters. Normalization of units was carried out to identify the relative influence of each parameter on the probability of such noise occurring. Further, re-logistic regression was performed with parameters selected based on the c2 test. The classification of the air conditioner refrigerant noise is important because appropriate measures can be chosen by the refrigerant noise classification. The water sound has low-frequency characteristics and the gas sound has high-frequency characteristics. There are differences in improvement of two noises. Therefore, a clear distinction must be made between the refrigerant noises to reduce mistakes in improvement. Probability-based optimal cutoff values were determined for the classification of water and gas sounds. Air-conditioning refrigerant noise was classified by taking into account the logistic regression and cutoffs. New experiments on the generation of refrigerant noise were conducted to validate the logistic regression classification. Data obtained from the experiments were classified at an accuracy level of 95.1%.

자동차 에어컨 냉매 가스 누설에 대한 고장사례 고찰

이 논문의 목적은 자동차 에어컨 가스 누설에 관련된 고장사례를 분석하고 고찰한 것이다. 첫 번째 사례는 냉매가 누설된 상태에서 에어컨 컴프레서가 계속 작동되었다. 이로 인해 에어컨 컴프레서 내부의 피스톤이 윤활부족으로 인해 피스톤이 부분적으로 에어컨 컴프레서 내부의 실린더에 소착되는 현상이 발생하였다. 이것이 엔진작동 중 부하를 증대시켜 엔진의 회전수 변동과 함께 엔진의 작동이 정지되는 현상이 발생된 것으로 확인되었다. 두 번째 사례는 에어컨 라인과 관련 시스템을 확인한 결과 에어컨 컴프레서에서 뒤쪽으로 가는 컨덴서 고압파이프에서 미세한 균열에 의해 에어컨 냉매 가스가 누설되는 것을 확인하였다. 세 번째 사례는 에어컨 컨덴서 핀 부에서 육안으로 확인하기 어려운 미세한 크랙에 의해 컨덴서 내부 안쪽에서 에어컨 가스가 미세하게 누설되는 것을 확인하였다. 따라서, 에어컨 시스템은 에어컨 냉매가스에 의해 자동차의 실내의 온도를 낮춰 공기조화를 하는 시스템이므로 최적의 상태를 유지할 수 있도록 철저한 관리를 하도록 하여야 한다. This paper is to analyze and study the failure examples of refrigerant gas in automotive air conditioner. The first example, the air conditioner compressor continually operated that the refrigerant was leaked in air conditioner system. By lubrication shortage, the piston was partially sticked on cylinder of air conditioner compressor inner part. This was caused the phenomenon of engine operation trouble by load increasing with engine rpm variation during engine running. The second example, it sought the fact that the air conditioner refrigerant gas was leaked from air conditioner compressor to condenser high pressure pipe toward rear air conditioner checking with the lines of air conditioner. The third example, the refrigerant gas of air conditioner found that was leaked imperceptible from condenser inner by crack that was generated on the fins of air conditioner condenser. Therefore, the air conditioner system that maintain the air conditioner by decreasing the in-car temperature must meticulously manage to not leak the air conditioner refrigerant gas.

Analysis of Indoor Environment Safety with R32 Leaking from a Running Air Conditioner

This paper, in the view of indoor security, analyzes the leak variation and indoor R32 concentration distribution when it leaks from the running indoor unit using experimental methods. The results show that the leak rate of R32 decreases with the air conditioner operating. And the leak process of refrigerant under operating conditions can be classified into two stages, fast leak stage and slow leak stage. The concentration of test points increases at first, then decreases and gradually stabilizes. Near the leak hole, it is the highest and varies dramatically. And it is high in the supply air mine stream, but it is only about 15% of the LFL. The concentration of the corner that the supply air cannot reached is the lowest. The indoor security during the leaking process of R32 is evaluated, and the results show that the combustible zone only appears near the leak hole, and its duration is very short. Ignition experiment is took in the combustible region and the results show that the candle flame and spark diffuse slightly, but it cannot spread effectively. It can be concluded that the hazard of using R32 as the refrigerant of air conditioner is low with the air velocity and angle keeping at 5.8m/s and 25°. In order to improve the security of the indoor environment further, the paper also analysis the impact of exhaust on indoor R32 concentration distribution and the results indicate that ventilation can reduce the indoor R32concentrationeffectively. Thus, it can reduce the risk of fire by opening the exhaust fan when R32 leaks with the air conditioner running.

Cycle performance of alternative refrigerants for domestic air-conditioning system based on a small finned tube heat exchanger

In order to find alternative refrigerants which exhibit both favorable cycle performance and environmental friendliness, R32 and R290 were utilized to contrast to R22 and R410A as substitutes in the present study. The experiments were conducted with a 5 mm finned tube heat exchanger based on the enthalpy method in a small split household air conditioner. The results showed that in nominal cooling conditions, the COPR of R32 and R290 were 26.8% and 20.4% higher than R22, 7.3% and 2.1% higher than R410A. And in nominal heating conditions, the COPHR of R32 and R290 were both 11.0% higher than R22, 5.3% higher than R410A. The systems with R290 and R32 have similar capacities to that with R22 and R410A in heating mode, but a relatively huge difference of capacities in cooling mode. In consideration of charge amount, R290 could be considered as the most superior alternative refrigerant in air conditioners with the small finned tube heat exchanger.

Air Conditioner Refrigerant Inhalation: A Habit with Chilling Consequences

Inhalant abuse has long been regarded as a concerning form of substance abuse in teenagers and young adults, and is now becoming increasingly prevalent in the adult population. Inhalants are readily available in various household products, although acquisition of these items in any significant quantity can be costly and raise suspicion for abuse. Here, we report the case of a man who reported abusing air conditioner fluid and review the available literature on this form of inhalant abuse.

ろう付加熱後に180℃熱処理したAl–Mn–Cu系合金の粒界腐食感受性

The alternation of an air-conditioner refrigerant from a freon-based refrigerant to CO2 is proposed. A maximum temperature in the CO2 heat-exchange cycle approaches to 180°C after brazing, which might affect susceptibility to intergranular corrosion. In this work, the intergranular corrosion susceptibility of Al–Mn–Cu alloys heat treated at 180°C after brazing was investigated. In both of the heat treated and non-treated Al–Mn–Cu alloys, Al–Cu intermetallic compounds were observed at grain boundaries, while in the non-treated Al–Mn–Cu alloys, Al–Mn intermetallic compounds also existed at the grain boundaries, being in contact with the Al–Cu compounds. The observation indicates that the Al–Mn compounds promote precipitation of the Al–Cu compounds at the grain boundaries. It also means development of Cu depleted zone along the grain boundaries. However, the intergranular corrosion susceptibility was decreased when the heat-treatment time become longer because Cu solid solubility in the grains decreased down to the same level of the Cu depleted zone. With the Mn concentration, the decreasing rate is accelerated and the time needed to show no susceptibility is shortened.

냉매 내 수분의 혼입량이 차량 에어컨의 냉각성능에 미치는 영향

This study was conducted to figure out the diagnosis basis of cooling performance depending on water amount in the refrigerant of air conditioner, which can be estimated by the temperatures and pressures along the refrigerant circulation line. A car air conditioner of SONATA III (Hyundai motor Co., Korea) was tested at maximum cooling condition at the engine speed of 1500 rpm in the room controlled at 33~<TEX>$35^{\circ}C$</TEX> air temperature and 55~57% relative humidity conditionally. Measured variables were temperature differences between inlet and outlet pipe surfaces of the compressor, condenser, receive drier and evaporator; and high pressure and low pressure in the refrigerant circulation line; and temperature difference between inlet and outlet air of the cooling vent of evaporator. In this study, changes of the water amount in the refrigerant were correlated to the temperatures and pressure changes and also water amount caused poor cooling performance. As water amount increased in the refrigerant in the air conditioner, the performance of the cooling or the heat transfer became worse. Temporal variations of the surface temperature of the evaporator outlet pipe and the low-side pressure showed various patterns that could estimate the water amount. When the water amount caused bad cooling performance, the patterns of the temperature of the evaporator outlet pipe indicated irregular fluctuation greater than <TEX>$5^{\circ}C$</TEX>. When the diagnosis system is using just external sensors of the low-side pressure and the temperatures of inlet and outlet air of cooling vent of the evaporator, the precise pattern of bad cooling performance caused by excess water amount in the cooling line was irregular pressure fluctuation, 25 kPa under 120 kPa, and temperature, <TEX>$12^{\circ}C$</TEX> and less.

냉매 내 공기혼입에 따른 에어컨 시스템의 냉각성능 저하

This study was performed to present the diagnosis basis of cooling performance deficiency according to air quantity included in refrigerant of air-conditioner by detecting the temperatures and pressures of refrigerant pipeline. The car air-conditioner of SONATA III (Hyundai motor Co., Korea) was tested by maximum cooling condition at 1500 rpm of engine speed in the room with controlled air condition at and 55~57% RH. Measured variables were temperature differences between inlet and outlet pipe surface of the compressor (Tcom), condenser (Tcon), receive dryer (Trec) and evaporator (Teva), and high pressure (HP) and low pressure (LP) in the refrigerant pipeline, and temperature difference (Tcoo) between inlet and outlet air of the cooling vent of evaporator. Control variables were the refrigerant charging weight and the vacuum degree in the refrigerant pipeline before charging refrigerant. From the test, it was represented that the measuring values of (Tcom), LP and (Tcoo) were enabled to make the diagnosis of cooling performance deficiency according to quantity included in refrigerant of air-conditioner. The ranges of Tcom, LP and Tcoo to make the diagnosis of cooling performance deficiency were respectively less than , more than 166.7 kPa-g(1.7 kgf/) and less than . In the case of using only external sensors and the condition under the normal performances of air conditioner, it was considered that the ranges of LP and Tcoo to make the diagnosis of cooling performance deficiency were respectively more than 166.7 Pa and less than .

生体影響紫外線DUVの特別特性解析 : 金沢における紫外域日射及び気象観測データを用いて

Today, the ozone depletion in the stratosphere is recognized as a major environmental problem, because which results in a significant increase in solar ultraviolet (UV) radiation that reaches the surface of the Earth. The CFC utilized as a refrigerant of air conditioner causes the ozone layer depletion. The purpose of this study is to clarify the change with the time in the clear sky day on DUV, which is one index of the biologically weighted ultraviolet solar radiation, in order to make the ultraviolet radiation defense effective at the individual action level. Through analysis of observed spectral ultraviolet irradiances, UV-B, UV-A and global solar radiation at Kanazawa Institute of Technology, the followings were shown : (1) The distinctive feature of DUV change by the time in a day compared to global solar radiation. (2) The difference of DUV values per unit flux of global solar radiation by the season. (3) The existence of the size of DUV value between morning and afternoon.

Performance evaluation of heat exchanger using alternative refrigerant R407C

AbstractR22 (HCFC22) has been widely used as the refrigerant in air conditioners. According to the Montreal protocol for ozone layer protection, the total production of HCFCs has been capped since the beginning of 1996. Zeotropic refrigerant mixture R407C and nearly azeotropic refrigerant mixture R410A have been selected as alternatives to R22.We examined refrigerant passages in heat exchangers used in heat pump‐type room air conditioners using zeotropic refrigerant R407C through simulation, and obtained the following conclusions. In an indoor heat exchanger, a counter flow configuration when operating as a condenser has higher temperature efficiency. When an outdoor heat exchanger operates as an evaporator, a configuration that suppresses the temperature glide by partially reducing the refrigerant passage not only produces high efficiency, but also reduces the frost formation on fins. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(8): 626–638, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10064