Air Conditioning Industry Research Articles

Optical and Structural Properties of V2O5 Electrochromic Thin Films

The increase in global temperature has led to a significant surge in energy consumption within the air conditioning industry, resulting in environmental deterioration. Electrochromic (EC) windows have emerged as a promising solution to address these challenges. Vanadium pentoxide (V2O5) stands out among all metal oxide materials due to its remarkable EC properties, including substantial Li+ ion insertion capacity and multicolor capabilities. Despite the potential of V2O5, there remains a lack of comprehensive research on the structural and optical properties of V2O5 films with varying thicknesses. Therefore, this study aims to investigate the structural and optical properties of V2O5 thin films with thicknesses ranging from 46 to 344 nm. By employing the sol-gel spin coating method, V2O5 thin films were fabricated and analyzed using X-ray diffraction (XRD) spectroscopy and ultraviolet-visible (UV-Vis) spectrophotometry. The fabricated V2O5 thin films with thicknesses of 46-274 nm demonstrated an average film transparency of 83 %. XRD analysis further revealed that the V2O5 thin films reached their peak crystallinity at a thickness of 344 nm. Moreover, CV analysis revealed that the V2O5 device, with a thickness of 274 nm, exhibited a cathodic peak current of -1.63 mA, indicating its excellent ability to facilitate Li+ ion diffusion. Additionally, CA measurements displayed a high optical modulation of 37.78 %. Ultimately, this research contributes to the development of energy-efficient solutions for sustainable environmental practices.

Leading the Transition from Halogen Refrigerants to Natural Refrigerants in Indonesia (Pertamina Plaju Refinery as a Pioneer)

Abstract Climate change has become a worldwide concern, prompting Indonesia to take ambitious actions to reduce emissions and control rising temperatures. The rapid growth of the Refrigeration and Air Conditioning (RAC) industry in Indonesia has led to higher greenhouse gas emissions. To tackle these environmental challenges, Pertamina Plaju Refinery is manufacturing natural refrigerants, specifically Musicool (Propane) and Breezone (Propylene), providing sustainable replacements for R-22 and R-32. Pertamina Plaju Refinery has made several process modifications and optimizations to support the production of Musicool and Breezone in the Alkylation and Purification Units. These modifications involve optimizing operating conditions and implementing necessary infrastructure changes. In general, Pertamina’s natural refrigerants consume 20-30% less energy than halogen refrigerants while offering similar cooling capacity to R-22 and R-32. Propane and Propylene-based refrigerants have the lowest impact on global warming and are eco-friendly due to their easy degradation process. Musicool and Breezone, having an ODP of 0.0, with maximum GWP of 3.3, indicating minimal contribution to ozone depletion. Pertamina’s efforts to engage and reach potential customers on these natural refrigerants, involve collaborative efforts among various organizations, including with all District Office Plaju, South Sumatra.

Research on energy-saving and carbon-reducing technologies for water-ground source heat pump units

Abstract The heat pump industry’s energy consumption as a percentage of total energy consumption is constantly increasing. Research on energy-saving and carbon-reducing technologies, and manufacturing high-efficiency units of heat pump with water-ground source has become the main trend of the current heat pump industry. With proposal of the national “dual-carbon” strategy goal, enhancing the energy efficiency of units of heat pump with water-ground source has become a key way to transform and upgrade the refrigeration and air conditioning industry. The aim of this study is to combine current studies on energy-saving and carbon-reducing technologies for units of heat pump with water-ground source and applying these technologies. Through experimental tests, the energy efficiency of units of heat pump with water-ground source is more than 15% higher than that of ordinary units.

Thermoeconomic model for diagnostic techniques to evaluated vapor compression refrigeration system performance

In recent years, it has been possible to observe a significant expansion of the refrigeration and air conditioning industry. Considering that food refrigeration systems (blast chilling or freezing, cold storage, retail display, etc.) and air conditioners are large energy consumers, this work presents a methodology for evaluating the performance and behaviour of these systems using the thermoeconomic diagnosis concept. The thermoeconomic model used allowed the definition of the condenser and expansion device products, which is not trivial for these components. With that, the thermoeconomic diagnosis was used to evaluate the degradation of refrigeration system components, together with the influence of individual component degradations on efficiency, cooling capacity, operating parameters, and power consumption of the whole system. Through this analysis, a prognosis of system behaviour was obtained, which can be used for maintenance scheduling, as well as for the comprehensive energetic and exergetic analysis of a refrigeration system and each of its components.

Fluid-to-fluid similarity and CFD predictions of surrogate fluid as a replacement for R11 refrigerant used in a subcooled flow boiling analysis: Validation against reference experimental data

In this study, we present the possibility of substituting the primary fluid Freon 11 (CCl3F, R11) used in the experimental thermohydraulic test facility which offers the advantage to obtain phase change at relatively low heat fluxes and pressure if compared to water working fluid. Nevertheless, R11 is a CFC (Chlorofluorocarbures) part of the gases that contribute to the degradation of the ozone layer.For this purpose, four working fluids (non-CFC) are judiciously selected to replace the R11, namely the R123, R134a, R143a and CO2, and this through multidimensional Computational Fluid Dynamics (CFD) modeling of steady state flow boiling phenomenon. The calculation model covers a wide range of mass fluxes (435 – 1443 kg/m2s) and heat fluxes (1.2– 36 W/cm2); it predicts the heat transfer rates and transitions points for each flow regime. In this research, the experiment's data were compared to the outcomes of Ansys-CFX computations, using a steady Reynolds-Averaged Navier-Stokes (Steady-RANS) model, to investigate the best replacement refrigerant for R11. The turbulence effects on the mean flow and near wall are taken into consideration using the Shear Stress Transport (SST k-ω) turbulence model. The results from the four fluids were transposed to their water equivalent and compared to those deduced from the experimentation and correlations available in the literature to select the appropriate substitution fluid. The results qualitative and quantitative for vertical and horizontal subcooled boiling flow at the CHF location show that, the most effective surrogate fluid is R123 (HCFC), is still widely used in the refrigeration and air-conditioning industry, then R134a (HFC), then R143a (HFC).

Analyzing global competitiveness of Turkish air conditioning industry

The global economy significantly relies on the air conditioning sector, which has been gaining increased importance worldwide and in Türkiye due to the impact of global warming, climate change, and the diminishing energy resources. As a multifaceted industry encompassing air conditioning, heating, installation, insulation, refrigeration and ventilation sector has been adapting to the growing demand for environmentally friendly and energy-efficient solutions. This study analyzes air conditioning industry of Türkiye and its sub-product groups in terms of its ability to compete internationally, spanning from 2001 to 2021. To assess competitiveness, we employed various analytical tools, including Balassa's Revealed Comparative Advantages Index (RCA), Vollrath Indices (RXA, RMP, RTA, RC), Revealed Symmetric Comparative Advantages Index (RSCA), Trade Balance Index (TBI), and Product Mapping method. Notably, there is no research that scrutinize the competitiveness of the Turkish air conditioning industry utilizing the Product Mapping. The study findings emphasize that air conditioning industry of Türkiye has competitiveness. Within the sub-product group, the analysis reveals that Türkiye has competitiveness for 11 products, a near-limit competitiveness for 3 products, and a lack of competitiveness for 10 products.

SIMULATION ANALYSIS OF SHELL AND TUBE HEAT EXCHANGER USING DIFFERENT FLUIDS

There are many models to characterize the behavior of the heat exchangers encountered in many industries. There are several correlations available, so that the heat transferred and the thermal stresses can be evaluated. Shell and Tube heat exchangers are having special importance in boilers, oil coolers, condensers, and pre -heaters. They are also widely used in process applications as well as the refrigeration and air conditioning industry. The robustness and medium weighted shape of Shell and Tube heat exchangers make them well suited for high pressure operations. The present work deals with the design and analysis of water-cooled shell and tube condenser and we have shown how to done the thermal analysis by using theoretical formula, for this we have chosen an industrial problem of 8 ton capacity of counter flow shell and tube heat exchanger of water type. The condenser is designed using theoretical procedures. The condenser is modeled by using the dimensions obtained from the design procedures. Then thermal analysis is carried out in SOLIDWORK flow simulation. The results obtained through the analysis are discussed in detail and compared with analytic values. .Key Words: Heat exchanger, Perforated rings, Reynolds number, Overall heat transfer coefficient.

Assessing the Skillset Impacting the Readiness of HVAC Bachelor's Final Year Students for Industrial Revolution 4.0 (IR 4.0)

The Industrial Revolution 4.0 (IR 4.0) is a significant period of industrial progress marked by advanced technologies like the Internet of Things (IoT) and Cyber-Physical Systems (CPS). The current change presents significant challenges and opportunities for various sectors, including the Heating, Ventilation, and Air Conditioning (HVAC) industry. Addressing the readiness of HVAC students for IR 4.0, this study investigates the gap in skills and competencies required in this new era. This study primarily assesses the readiness of final-year bachelor’s degree students in HVAC, focusing on balancing technical and non-technical skills. Employing a qualitative descriptive research design, the study involved 100 final-year HVAC students from Universiti Tun Hussein Onn Malaysia (UTHM) and Universiti Teknikal Malaysia Melaka (UTeM). A structured questionnaire, developed based on a thorough literature review and validated through expert reviews and a pilot study, was used to collect data. The questionnaire assessed students' self-evaluation of their readiness, understanding of technical skills, and developing non-technical skills relevant to IR 4.0. The analysis revealed that students possess a high level of perceived readiness for IR 4.0, with non-technical skills emerging as significant contributors to their readiness. These skills accounted for 44% of the variance in students' readiness. The findings underscore the importance of integrating non-technical skills into the HVAC curriculum, highlighting their role in equipping students to navigate the evolving technological landscape of IR 4.0. In conclusion, the study provides comprehensive insights into the skillsets necessary for HVAC students to thrive in the IR 4.0 era. It emphasises the need for educational institutions to adapt their curricula and pedagogical strategies to include a balanced focus on technical and non-technical skills, thereby enhancing student employability and readiness for the challenges of the modern industrial world.

Evaluation of large language models (LLMs) on the mastery of knowledge and skills in the heating, ventilation and air conditioning (HVAC) industry

Large language models (LLMs) have shown human-level capabilities in solving various complex tasks. However, it is still unknown whether state-of-the-art LLMs master sufficient knowledge related to heating, ventilation and air conditioning (HVAC) systems. It will be inspiring if LLMs can think and learn like professionals in the HVAC industry. Hence, this study investigates the performance of LLMs on mastering the knowledge and skills related to the HVAC industry by letting them take the ASHRAE Certified HVAC Designer examination, an authoritative examination in the HVAC industry. Three key knowledge capabilities are explored: recall, analysis and application. Twelve representative LLMs are tested such as GPT-3.5, GPT-4 and LLaMA. According to the results, GPT-4 passes the ASHRAE Certified HVAC Designer examination with scores from 74 to 78, which is higher than about half of human examinees. Besides, GPT-3.5 passes the examination twice out of five times. It demonstrates that some LLMs such as GPT-4 and GPT-3.5 have great potential to assist or replace humans in designing and operating HVAC systems. However, they still make some mistakes sometimes due to the lack of knowledge, poor reasoning capabilities and unsatisfactory equation calculation abilities. Accordingly, four future research directions are proposed to reveal how to utilize and improve LLMs in the HVAC industry: teaching LLMs to use design tools or software in the HVAC industry, enabling LLMs to read and analyze the operational data from HVAC systems, developing tailored corpuses for the HVAC industry, and assessing the performance of LLMs in real-world HVAC design and operation scenarios.

Research on heat transfer property of air-air micro channel evaporator

Heat exchanger with air-air micro channel is widely used in the refrigeration and air-conditioning industries due to its excellent energy saving and low cost. Recent researches on the air-air micro channel has achieved some available correlations to solve heat transfer coefficient in the channel. However, the available correlations cannot correspond our heat exchanger because the heat transfer for two-phase flow in the micro channel is complex. In this paper, we manufactured an evaporator with the aluminum micro channel heat exchanger and tested its heat transfer efficiency. The heat exchanger, which was filled with R32 as the working fluid, was characterized with the liquid filling ratio [Formula: see text] ranging from 0.21 to 0.61. We also investigated the thermal performance of the heat exchanger under various temperature differences of the cold and hot air inlets, which ranges from 3°C to 21°C. The experimental results show that the internal boiling heat transfer coefficient increases first and then decreases, with the increasing of liquid filling ratio and the increasing of temperature. On basis of the experimental data, we obtained a new correlation associating with the liquid filling ratio and the temperature difference, which can be used to predict the heat transfer coefficient in the channel. Comparing the predicted value from our correlation with the experimental data, around 88% experimental data falls in the ±15% error bands and the mean absolute error is 7.91%.

Optimization of lithium adsorption from seawater via aluminum chloride as adsorbent using response surface methodology

ABSTRACT Lithium extraction from natural resources is an accelerating field of research owing to its growing demand in the medical, nuclear, battery, and air conditioning industries. Lithium compounds are used in various industries, including ceramics, glass, lubricant gases, rocket propellant, and aluminum production. The extraction of lithium from seawater via adsorption using AlCl3.6 H2O as an adsorbent is investigated in this study. The effect of process parameters such as pH, temperature, contact time, the molar ratio ([Al3+]/[Li+]), and stirring rate on process efficiency is investigated and optimized. The response surface methodology (RSM) is used to investigate the effects of operating parameters and choose the optimal configuration. A standard synthetic solution containing 50 ppm lithium is prepared and experimented with facilitating comprehension of the procedure. The adsorption efficiency of a synthetic solution is 88% at optimized values, while that of seawater is 78.5%. Seawater has a lower efficiency because it contains ions such as Mg2+, Ca2+, K+, and Na+ that compete for active points/sites during adsorption with lithium ions (Li+).

Chair Fans as Energy Efficient Strategy to Aid Localized Ventilation

Nowadays, the air conditioning industry is deviating from the conventional mixing ventilation technique towards localized ventilation. Displacement ventilation and ceiling personalized ventilation are localized systems presenting a high potential in insuring good indoor air quality while reducing the energy consumption compared to mixing ventilation. In this work it is proposed to enhance their performance by assisting them with chair fans controlling the behavior of occupants’ convective plumes. Computational fluid dynamics models were developed to simulate office spaces ventilated by displacement ventilation and ceiling personalized ventilation equipped with chair fans. The Lagrangian technique was adopted to track particle trajectories to determine particle behavior after generation from occupant respiratory activity. A parametric study was conducted to assess the effect of chair fan flow rate on each system performance in terms of indoor air quality. Recommendations were given to reduce cross-infection between occupants for both types of localized systems studied with reduced energy consumption. The total chair fans flow rate was optimized for both cases to insure acceptable indoor air quality resulting in significant energy savings. It was found that the optimal total chair fans flow rate per occupant was approximately 14 L/s when assisting displacement ventilation while it was 10 L/s when aiding ceiling personalized ventilation.

Implementation of Fluidized Bed Concept to Improve Heat Transfer in Ecological Adsorption Cooling and Desalination Systems

Sustainable development policy focuses on reducing the carbon footprint generated by the global industry and energy sector. Replacing conventional energy sources with environmentally friendly ones requires advanced research to increase energy efficiency and reduce the instability and intermittence of renewable sources. Moreover, adsorption chillers are an opportunity to introduce net-zero emission technologies to the refrigeration, air-conditioning, and desalination industries. Adsorption devices could be popularized if a method of effective heat transfer in the volume of the adsorption bed is developed. The innovative concept of introducing fluidized beds into the adsorption system can achieve the most promising results in improving energy efficiency. To confirm the adopted assumption, heat transfer coefficient calculations for the packed and fluidized bed were carried out in this paper based on experimental tests and literature data. The empirical research aims to extend the fundamental knowledge in the implementation of fluidization under low-pressure conditions, characteristic of the adsorption systems’ working cycle. Experiments were conducted on a unique test stand equipped with the Intensified Heat Transfer Adsorption Bed (IHTAB) reactor prototype. Five adsorption bed samples were analyzed. The reference sample consisted only of silica gel, and the subsequent ones contained aluminum or carbon nanotubes with 5 and 10% additions. In the case of samples with admixtures, the fluidized state increased the heat transfer coefficient on average from approx. 36.9 W/m2 K to approx. 245.4 W/m2 K.

Recycling air conditioner-generated condensate water for microalgal biomass production and carbon dioxide sequestration

Air conditioners alleviate the discomfort of human beings from heat waves that are consequences of climate change caused by anthropogenic activities. With each passing year, the effects of global warming worsen, increasing the growth of air conditioning industry. Air conditioning units produce substantial amounts of non-nutritive and (generally) neglected condensate water and greenhouse gases. Considering this, the study explored the potential of using air conditioner condensate water (ACW) to cultivate Chlorella sorokiniana, producing biomass, and sequestering carbon dioxide (CO2). The maximum biomass production was obtained in the BG11 medium (1.45 g L−1), followed by ACW-50 (1.3 g L−1). Similarly, the highest chlorophyll-a content was observed in the BG11 medium (11 μg mL−1), followed by ACW-50 (9.11 μg mL−1). The ACW-50 cultures proved to be better adapted to physiological stress (Fv/Fm > 0.5) and can be suitable for achieving maximum biomass with adequate lipid, protein, and carbohydrate production. Moreover, C. sorokiniana demonstrated higher lipid and carbohydrate yields in the ACW-50 medium, while biomass production and protein yields were comparable to the BG11 medium. The lipid, protein, and carbohydrate productivity were 23.43, 32.9, and 23.19 mg L−1 d−1, respectively for ACW-50. Estimation of carbon capture potential through this approach equals to 9.5% of the total emissions which is an added advantage The results indicated that ACW could be effectively utilized for microalgae cultivation, reducing the reliance on freshwater for large-scale microalgal biomass production and reduce the carbon footprints of the air conditioning industry.

Collaborative Reconfiguration of Supply Networks Based on GNN and ALC

With the prevalence of lean and just-in-time principles, traditional supply chains often exhibit inflexibility, leading to challenges in satisfying extensive customized orders and managing risks during disruptions. Thus, there is a need for a more flexible, resilient, and collaborative network and strategies to tackle the aforementioned challenges. In this study, we introduce a new supply network called the industry supply chain, aimed at enabling collaborative decision-making and dynamic reconfiguration. We create a graph neural network model to promptly identify sudden disturbances and devise a distributed multidisciplinary optimization model to facilitate collaborative reconfiguration. The experimental findings from an air-conditioning industry supply chain show that network reconfiguration under real-time disturbance detection reduces losses and improves operational stability.

The Impact of RMB Exchange Rate Fluctuation on China's Air Conditioning Industry

Based on the background of China's current trade with other countries is becoming increasingly close, the study of exchange rate stability on the impact of China's trade with other countries to promote China's economic stability has a certain theoretical significance. In the study of air conditioning industry import and export trade factors affecting the attention of the national exchange rate is very important, in the two countries trade relations, the exchange rate is a measure of the two countries to buy, sell the price of the product of the vital factors, exchange rate changes for the enterprise will bring a certain degree of impact, stabilization of the exchange rate for the promotion of our country and the trade of other countries in the long term and good cooperation has important practical significance. The air-conditioning manufacturing industry is a very representative research object. The cost-sensitive home appliance industry is a labor-intensive industry, which provides a huge number of jobs for China and creates a huge amount of foreign exchange income. At the same time, the home appliance industry, as a representative of China's manufacturing industry, faces industrial upgrading pressure and is in the maturity of a fully competitive industry, which has been severely impacted by exchange rate changes. It is of great significance to correctly measure and analyze the foreign exchange risk exposure of the import and export of the air-conditioning industry and its influencing factors. From a micro point of view, enterprises can be based on foreign exchange risk exposure situation targeted adjustment of financial strategies, strategies and management methods. From a macro point of view, the country can be based on the overall foreign exchange risk exposure characteristics of home appliances to formulate the correct macroeconomic policy.

Multi-group decision-making approach for evaluating brand collaboration requirements of large-scale manufacturing industrial value chain

Brand collaboration requirement (BCR) evaluation is a key premise for core manufacturing enterprises to lead the collaborative brand construction of a large-scale manufacturing industry value chain (LSMIVC). Because brand collaboration (BC) in LSMIVC requires interaction with other businesses, BCRs are interactional and decision-makers come from multiple groups. However, existing requirement evaluation approaches rarely consider the interactional nature of requirements and the multiple groups nature of decision makers, producing unstable, easy-to-fail, and inaccurate results. Therefore, this study presents a multi-group decision-making approach based on a decision-making trial and evaluation laboratory and analytic network process (DEMATEL-ANP). This approach integrates the assessment information of BCRs from group decision-makers and prevents unstable and easily invalid assessment results owing to an incomplete decision-maker team. Additionally, DEMATEL-ANP was used to rank the interaction BCRs, which improved the accuracy and effectiveness of the requirement evaluation. Finally, the developed approach and model were tested against the air-conditioning industry value chain. The case study shows that the proposed method can determine requirement ranking. Comparative tests show that the proposed approach is effective and superior, and is more consistent with real-world BC situations. Therefore, the proposed approach provides a direction and theoretical basis for core manufacturing enterprises to implement BC.

Assessing the Impact of Data Sciences and Smart Technologies in Air Conditioning Project Management: A Delphi Method Analysis within the Construction Industry

The integration of data sciences and smart technologies in the construction industry, particularly in air conditioning project management, is an important area of research. This study employs the Delphi Method to explore this integration, surveying 40 experts in construction management. Participants were meticulously selected based on a set of inclusion criteria related to age, educational qualifications, and field experience. The study tests five hypotheses, each scrutinized through a score-based Delphi analysis. The findings are mixed and shed new light on several dimensions of air conditioning project management. For instance, the study refutes the commonly held belief that the location of air conditioning projects significantly impacts worker safety. It also challenges the assumption that exceeding international safety standards like ISO leads to cost savings. On the other hand, the study validates the significance of global safety standards and the undeniable role of data sciences and smart technologies in enhancing human safety in the air conditioning industry. These findings not only challenge existing models, but also open avenues for further research. They indicate a complex interplay between safety, cost-effectiveness, and technological integration in air conditioning project management. The study suggests a shift towards data-driven decision-making and underscores the need for international safety standards, particularly in an era marked by rapid technological advancements and globalization.

Corporate image, customer satisfaction and loyalty among customers in air conditioner industry: Basis for customer relationship management model

Corporate image, customer satisfaction and loyalty among customers in air conditioner industry: Basis for customer relationship management model

Comparison of Thermal Effectiveness and Crevice Corrosion Risk of Fin Geometry on All-Aluminum Microchannel Heat Exchangers

All-aluminum microchannel heat exchangers have recently gained popularity in the heating, ventilation, and air conditioning industry. Despite their attractive thermal performance design, these heat exchangers make coils used in automotive, commercial, and residential applications prone to crevice corrosion. This study uses high-fidelity conjugate heat transfer simulations to model a micro channel heat exchanger system that includes fins and tubes with crossflow to compare their thermal effectiveness to gain insight into potential crevice corrosion of the MCHE alloy. This study considers three fin geometries (louver, step, and saw) with the same tube and circular shape microchannel and identifies the corrosion hot spot and thermal effectiveness. A predicted flow field also identifies crevices between fins and tube surfaces as critical corrosion hot spots often associated with low-velocity regions. The crevice volumes for the louver, step, and saw fin shapes are calculated as respectively. Results also show that the same circular microchannel louver shape fin has higher effectiveness than the step and saw shape fin. The thermal effectiveness for microchannel tubes with louver, step, and saw shape fins are 0.337, 0.20737, and 0.2895, respectively.