Air Conditioning Industry Research Articles

Fatigue and Mechanical Properties of Aluminium-Copper Bi-Metal Tubes

Metallurgical bonded aluminium-copper bi-metal tube has a future prospect as an alternative material to copper in the heat, ventilation and air-conditioning (HVAC) industries. The application of aluminum-copper bi-metallic material is seems practical in maintaining the quality of existing products. However, the mechanical strength and fatigue properties of the bi-metal tubes are unknown. In this study, metallurgical, mechanical and fatigue properties of the copper phosphorous alloy and aluminium-copper bi-metal tubes were characterized through metallographic analysis, tensile, bending and fatigue tests. The results show that there observed a weak and brittle Al-Cu intermetallic compound at the interlayer between Al and Cu. Tensile fracture surface observation revealed that separation of Cu from Al occurred at the interlayer. The bending properties of the tubes were influenced by the amount of volume fraction of Cu in the materials. Three point bending fatigue test results showed that a critical buckling stress is presents for tubes with diameter less than 12.7mm. The aluminium-copper bi-metal tubes show degradation of fatigue strength almost 55% as compared to that of Cu alloy tube.

A Critical Review on Condensation Heat Transfer in Microchannels and Minichannels

Condensation in microchannels and minichannels is widely used in small devices such as air-cooled condensers for the air-conditioning and automotive industry, in heat pipes, thermosyphons and other applications for system thermal control. Currently, many research centers all over the world are dealing with the structure and operation of compact refrigerating devices. This is in line with the trend of 21st century that is moving towards the use of energy-saving and environmentally friendly technical equipment. In the present study, a critical review on condensation heat transfer in microchannels and minichannels is presented. This review include a wide range of different parameters such as the channel diameter (d), the saturation temperature (Ts), the mass flux (G), the vapor quality (x), different working fluids like steam, CO2 or R744, FC72, R22, R410A, and R407C, various shapes such as circular and noncircular, different orientations like horizontal and vertical, and systems consist of either single or multiple channels. At the end, recommendations for future studies will be given. As a result, this paper cannot only be used as the starting point for the researcher interested in condensation heat transfer in microchannels and minichannels, but it also includes recommendations for future studies on condensation heat transfer in microchannels and minichannels.

INVESTIGATIONS ON THE PERFORMANCE OF VAPOUR COMPRESSION SYSTEM RETROFITTED WITH ZEOTROPIC REFRIGERANT R404A

The environmental impacts like global warming and ozone depletion has become a challenge to the refrigeration and air conditioning industry. Chloro Fluoro Carbons (CFCs) and Hydro Flouro Carbons (HCFCs) are referred to as an Ozone Depleting Substances (ODS) because once these gases are released into the environment and reach the stratosphere, depletes the ozone layer. This research paper aims to study the performance characteristics of an R12 (CFC) vapour compression refrigeration system retrofitted with zeotrope blend of refrigerant R404a, used for cooling liquids with five different configuration of capillaries of diameters 0.033", 0.036", 0.044", 0.050" and 0.30" (2 Way). The refrigerant R404a is an alternate refrigerant to CFCs and HCFCs as they are ozone friendly and have less Global Warming Potential (GWP) than R12 and R134a. The parameters employed in analysis of the performance characteristics are the Evaporator load (Qe), Coefficient of Performance (COP), Work done by the compressor (Wc) and Refrigeration Effect (RE). A detailed experimentation was carried out to compare the performance and effectiveness of the system using five different capillaries. The result obtained from the observation will help to identify the optimum diameter of capillary which could be used in the system to give the best performance.

Study on Microstructure and Tensile Properties of New Cu-Al Bi-Metal Tubes Versus Pure Copper Tubes

In recent years, heating, ventilation and air condition (HVAC) industries have attempted to find alternative materials such as aluminum for replacing copper metal because of a light weight metal with relatively lower market price compared to copper. This study characterizes microstructure and tensile properties of new Cu-Al bi-metal tubes (aluminum cladded copper (ACC) and copper cladded aluminum (CCA)) versus copper phosphorous alloy tube in order to estimate the possibility of implementing the composite tubes in heating, ventilation, and air conditioning industries. The result shows that Cu phosphorus alloy tubes has the highest tensile properties followed by CCA and ACC bi-metal tubes and different tube size does not affect the tensile properties of tube of the same type.

When the mirror gets misted up: Modularity and technological change

This study investigates how component technological change affects the relationship between product modularity and organizational modularity (the across-firm mirroring hypothesis). Studying the air conditioning industry, we show that the across-firm mirroring hypothesis does not hold for technologically dynamic components and the associated supply relationships. In this case, the mirror gets �misted up� with buyers and suppliers having recourse to information sharing even in the presence of highly modular components. Our study contributes to the debate on the organizational implications of modularity and its ramifications for the theory of the firm.

Study on Energy Materials with the Impact of Using Chilled Water Storage Systems on the Performance of Air Cooled Chillers

In the air conditioning (AC) industry chilled water storage (CWS) systems are one form of cool thermal storage technology that can be used to time shift the electrical load of the system from the peak day periods to off peak night time periods. In this paper the data for the actual exported and generated electrical energy obtained for the power stations has been used to estimate the electrical energy consumption and the peak electrical load of AC systems. It is estimated AC systems represent about 62% of the peak electrical load. The results demonstrate that CWS can reduce the peak electrical load of a chiller in an air cooled AC system by up to 100% and reduce the nominal chiller size by up to 33% depending up on the operating strategy adopted. This is achieved with only a 4% increase in power consumption of the chiller for all CWS strategies except for full storage where the energy consumption actually decreases by approximately 4%.

Grid deformation strategies for CFD analysis of screw compressors

Customized grid generation of twin screw machines for CFD analysis is widely used by the refrigeration and air-conditioning industry today, but is currently not suitable for topologies such as those of single screw, variable pitch or tri screw rotors. This paper investigates a technique called key-frame re-meshing that supplies pre-generated unstructured grids to the CFD solver at different time steps. To evaluate its accuracy, the results of an isentropic compression-expansion process in a reciprocating piston cylinder arrangement have been compared. Three strategies of grid deformation; diffusion equation mesh smoothing, user defined nodal displacement and key-frame remeshing have been assessed. There are many limitations to key-frame re-meshing. It requires time consuming pre-processing, has limited applicability to complex meshes and leads to inaccuracies in conservation of calculated variables. It was concluded that customized tools for generation of CFD grids are required for complex screw machines.

Dynamic Analysis of Condenser Assembly of Automobile Air Conditioning System Using CAE Tools

With the automotive air-conditioning industry aiming at higher levels of quality, cost effectiveness and a short time to market, the need for simulation is at an all time high. In the present work, the use of dynamics analysis is proposed in the simulation of the automobile air conditioning condenser assembly for the vibration loads. The condenser assembly has been analyzed using the standard testing conditions. The results revealed that the components of condenser assembly may fail due to resonance in dynamic analysis. Thereafter, the condenser assembly was optimized, resulting in a 2 % reduction in mass.

Carbon footprint attributed to aluminum substitution for copper in the Chinese indoor air conditioner industry

The replacement of copper by aluminum, which has a lower price, is becoming a developing trend in the Chinese indoor air conditioner industry. However, the significant greenhouse gas emission during aluminum production may restrict this development. Based on a life cycle assessment, we use the carbon footprint method to account for the carbon footprint attributed to copper and aluminum usage in the Chinese indoor air conditioner industry from 2000 to 2009. The results show that (1) the carbon footprint of the Chinese indoor air conditioner industry generally declined during this period mainly because of the improvement in copper and aluminum production technology; and (2) after 2004, the carbon sink forest costs of this industry became lower than the production costs mainly because of the rising copper price and the perennial stability of the aluminum price. Based on these results, we analyze the developing trend of aluminum substitution for copper and propose a cooperative control strategy to limit the carbon footprint and to guide the development of the Chinese indoor air conditioner industry.

A hybrid approach to minimising manufacturing costs - study in a heating ventilation and air conditioning industry

A leading producer of commercial air-conditioning equipment faces the need to update its sheet metal operations in support of its commercial chiller product line. Currently, the producer meets the majority of its sheet metal needs through in-house manufacturing operations. Thus, three basic alternatives confront the producer. Capital can be invested to maintain existing in-house operations. It could also be invested to develop outsource suppliers to completely fill the sheet metal requirements. Finally, an investment could be made involving substantial reliance on both in-house and outsource suppliers. To effectively analyse the true cost associated with each alternative, realistic cost structures are derived employing activity-based costing (ABC) techniques in conjunction with probabilistic market forecast data. The alternative including both in-house manufacturing and outsource suppliers was identified as optimal through linear programming (LP) techniques. The implementation of this optimal solution is then analysed using the programme evaluation and review technique (PERT).

A New Method to Design Cam Used in Automobile Heating, Ventilating and Cooling System

With the automotive air-conditioning industry aiming at better levels of quality, cost effectiveness and short time to market, the need for simulation is at an all time high. In the present study, the airflow control mechanism of an automotive heating, ventilating and cooling module for opening various doors/dampers were kinematically analyzed. A new method for cam design was developed which is faster and simpler than the existing oscillating link method. The existing design was modified for the same output using the new cam design method. It is shown that the torque required in the modified design is lesser than that in the existing design, thus lowering the effort required to rotate the cam from the control panel.

Integrating Managerial Pattern and Competitive Advantages: The Moderation of Competitive Inertia

In dynamic competition, the competitive inertia is determined by components both inside and outside of company. This paper investigated that, after integration, how can firm appropriately alter their integrating managerial pattern, according to competitive inertia, in order to achieve better advantages cause from integration. Through 10-year data of the oligopoly enterprises in airconditioner industry in China, the analysis demonstrated that, improving flexibilities of integration managerial pattern helps to build differentiation advantages, while negative to cost advantages; while firm competitive inertia grew, systematicness of integration managerial pattern would have positive effects on differentiation advantages, while negative on cost advantages. Key words : Integrating managerial pattern; Competitive dynamics; Competitive inertia; Competitive advantages

A New Evaluation Method Based on Dynamic Incentive Model and Its Application in Operation Performance Evaluation of Listed Companies

Previous studies of operating performance of listed companies usually adopt static comprehensive evaluation method but not dynamic evaluation method. Besides, the evaluation information is aggregated in a simple weighted method, without integration of management tool. Considering these two deficiencies, this paper puts forward a dynamic incentive evaluation model and applies it in the comprehensive evaluation of the operating performance of listed companies. The paper first introduces dynamic incentive evaluation model, and then carries out an empirical study, using the annual reports data (2005-2009) of 13 refrigeration and air-conditioning industry listed companies. The results indicate that, compared with the evaluation results of traditional static method and dynamic method, the evaluation results of dynamic incentive model can reflect the operating performance of listed companies more objectively and comprehensively. Thus this model achieves good evaluation effect and has practical value.

Indoor Air Conditioning Unit Air Flow Performance Study – Characterization of Cross Flow Fan Designs

A detailed characterization is carried out on a typical cross flow fan used in the Heating, Ventilation, and Air Conditioning (HVAC) industry, in order to understand the fan design in detail. The study is carried out numerically by use of the software FLUENT and followed by experimental validation. Appropriate grid size selection has done, the RMS error is less than 7%. From the study, it is concluded that the thickness of the blade determines the total flow area and flow rate delivered. When the internal blade angle is at 90°, shock free entry is incurred and maximum flow rate can be achieved. The external blade angle should be within 20 to 45 degrees, to avoid rapid drop of pressure coefficient and efficiency. Lastly, the formation of the eccentric vortex zone inside the cross flow fan and flow field pattern are observed. The forming location and size of the zone determines the total air flow rate delivered and the amount of flow leakage through the tongue. Thus, the efficiency of the fan is highly sensitive to the flow structure in this zone.

Recalibration technique for NDIR gas sensors without the need for gas standards

PurposeThe output of nearly all non‐dispersive infrared (NDIR) gas sensors deployed in the heating, ventilation, and air conditioning (HVAC) industry today cannot maintain their accuracy specifications within six months to a year. Consequently, all installed NDIR gas sensors must be re‐checked for accuracy over time at great costs. The purpose of this paper is to advance a novel technique for expeditiously recalibrating such installed NDIR gas sensors without the need for using any gas standards.Design/methodology/approachBy recognizing the fact that the calibration curve for absorption biased designed NDIR gas sensors comprises two distinct domains, namely an invariant NDIR absorption physics domain and a variant sensor components characteristics domain. By formulating a novel recalibration procedure which corrects only changes that have taken place in the variant sensor components characteristics domain over time, it is possible to recalibrate the sensor very rapidly and remotely via wireless or infrared means using only the gas concentration level surrounding the sensor as a reasonably accurate gas standard.FindingsImplementation of the currently described recalibration technique to a large number of absorption biased designed NDIR gas sensors has been carried out for over a year in the laboratory. Results of these experiments have unambiguously confirmed the capability and the accuracy of this novel recalibration technique.Originality/valueThe currently presented recalibration technique for absorption biased designed NDIR gas sensors is original and has never been published elsewhere. This technique significantly reduces the maintenance costs, inclusive of labor and material, for installed NDIR gas sensors that require periodic and mandatory accuracy commissioning over time.

Beyond the “Mirroring” Hypothesis: Product Modularity and Interorganizational Relations in the Air Conditioning Industry

This study explores whether, to what extent, and under which conditions modular products are associated with modular organizations (the “mirroring” hypothesis). We analyze the product and organizational architectures of three firms in the air conditioning industry through an original data set of 100 components and supply relationships. Applying a variety of regression methods, we show that, under the condition of product architecture stability at the component level, supplier relations for loosely coupled components are characterized by less information sharing, which implies that the degree of coupling of product components varies directly with the degree of coupling of organizations (the “mirroring” hypothesis). Also, the performance of supply relationships depends on the amount of buyer–supplier information sharing but not on the degree of component modularity, which supports the relational view and confirms that product modularity does not have unambiguous effects on organizational performance. Moreover, the degree of component modularity negatively moderates the impact of buyer–supplier information sharing on supplier-relationship performance, which confirms that component modularity works as an ex ante, embedded substitute for high-powered interorganizational integration mechanisms. Finally, contingent on firms' strategies, organizational structures, and capabilities, we argue that at the firm level, higher product modularity may be associated either with less information sharing with suppliers, which implies that the mirroring effect might hold also at the firm level, or with more information sharing with suppliers, which implies that there may be increasing returns to modularity in design efforts because of interorganizational integration (the “complementarity” hypothesis).

THERMAL ANALYSIS OF SHELL AND TUBE HEAT EXCHANGER USING MAT LAB AND FLOEFD SOFTWARE

In this paper, a simplified model for the study of thermal analysis [1] of shell-and-tubes heat exchangers of water and oil type is proposed..Shell and Tube heat exchangers are having special importance in boilers, oil coolers, condensers, 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. In this paper we have shown how to done the thermal analysis by using theoretical formulae for this we have chosen a practical problem of counter flow shell and tube heat exchanger of water and oil type, by using the data that come from theoretical formulae we have design[2] a model of shell and tube heat exchanger using Pro-e and done the thermal analysis by using Floefd software and comparing the result that obtained from Floefd software and theoretical formulae. For simplification of theoretical calculations we have also done a Matlab code which is useful for calculating the thermal analysis of a counter flow of water-oil type shell and tube heat exchanger.

Analysis of a new cross flow heat exchanger flow arrangement – Extension to several rows

The present paper presents a theoretical analysis of a cross flow heat exchanger with a new flow arrangement comprehending several tube rows. The thermal performance of the proposed flow arrangement is compared with the thermal performance of a typical counter cross flow arrangement that is used in chemical, refrigeration, automotive and air conditioning industries. The thermal performance comparison has been performed in terms of the following parameters: heat exchanger effectiveness and efficiency, dimensionless entropy generation, entransy dissipation number, and dimensionless local temperature differences. It is also shown that the uniformity of the temperature difference field leads to a higher thermal performance of the heat exchanger. In the present case this is accomplished thorough a different organization of the in-tube fluid circuits in the heat exchanger. The relation between the recently introduced “entransy dissipation number” and the conventional thermal effectiveness has been obtained in terms of the “number of transfer units”. A case study has been solved to quantitatively to obtain the temperature difference distribution over two rows units involving the proposed arrangement and the counter cross flow one. It has been shown that the proposed arrangement presents better thermal performance regardless the comparison parameter.

Performance assessment of an evaporative cooling-assisted window air conditioner

Substantial growth in refrigeration and air-conditioning industry has made a significant impact on net energy consumption. Condenser pressure is one of the critical parameters in the energy-efficient operation of refrigeration and air-conditioning systems. A novel system is developed to use the condensate, available at the cooling coil, for condenser cooling of a window air-conditioner unit by employing evaporative cooling. Performance testing of the system has shown 13% savings in energy and up to 18% enhancement in coefficient of performance. The maximum benefit of the evaporative cooling cycle over the basic cycle was found to be in the region of moderate climatic conditions. Copyright , Oxford University Press.

Making Consumers Comfortable: The Early Decades of Air Conditioning in the United States

During the air conditioner industry's first four decades, most installations were “commercial comfort” air conditioning systems, purchased by retailers to increase demand for their products. Air conditioning spread unevenly through the commercial sector and across the country. Using data from a variety of sources, I offer a quantitative account of this diffusion, viewed through an interpretive framework that emphasizes differences across geographic markets and industries in the costs and benefits to retailers of installing air conditioning. Correlates of early adoption of commercial air conditioning include electricity rates and consumer income and education levels.