Experimental and Theoretical Investigation of a Hybrid Compressor and Ejector Refrigeration System for Automotive Air Conditioning Application

In this research, performance of a hybrid compressor and ejector refrigeration system for automotive air conditioning application was investigated theoretically and experimentally. Mathematical modeling integrated the 1-dimensional analysis of ejector with the thermodynamic analysis of the hybrid compressor and ejector refrigeration system via EES (Engineering Equation Solver) software was proposed. Also an experimental rig of the hybrid compressor and ejector refrigeration system for automotive air conditioning application was built. This hybrid system has a rated cooling capacity of 3.5 kW. Refrigerant R134a and R141b were used for mechanical vapor compression sub system and the ejector sub system, respectively. The operating conditions are chosen accordingly as, generator temperature between 100 °C and 120 °C, condenser temperature between 30 °C and 40 °C, and evaporator temperature between 0 °C and 10 °C. Theoretical results of the ejector’s entrainment ratio (Rm) and COP of the system with variations on operating conditions were compared with the experiment values. From the results, mathematical modeling seems to provide error in COP prediction up to 15.5% when compared with experimental values. Fortunately, modification of the mathematical modeling by applying the computational fluid dynamics (CFD) technique provides less error about 5.5%. It’s also found that the COP of the hybrid system can be increased by 10-20% compared to a simple stage ejector refrigeration cycle (EJC). Moreover, estimated power consumption of the automotive air conditioning system can be approximately reduced 20% under the conventional vapor compression cycle.In this research, performance of a hybrid compressor and ejector refrigeration system for automotive air conditioning application was investigated theoretically and experimentally. Mathematical modeling integrated the 1-dimensional analysis of ejector with the thermodynamic analysis of the hybrid compressor and ejector refrigeration system via EES (Engineering Equation Solver) software was proposed. Also an experimental rig of the hybrid compressor and ejector refrigeration system for automotive air conditioning application was built. This hybrid system has a rated cooling capacity of 3.5 kW. Refrigerant R134a and R141b were used for mechanical vapor compression sub system and the ejector sub system, respectively. The operating conditions are chosen accordingly as, generator temperature between 100°C and 120°C, condenser temperature between 30°C and 40°C, and evaporator temperature between 0°C and 10°C. Theoretical results of the ejector's entrainment ratio (Rm) and COP of the system with variations on operating conditions were compared with the experiment values. From the results, mathematical modeling seems to provide error in COP prediction up to 15.5% when compared with experimental values. Fortunately, modification of the mathematical modeling by applying the computational fluid dynamics (CFD) technique provides less error about 5.5%. It's also found that the COP of the hybrid system can be increased by 10 - 20% compared to a simple stage ejector refrigeration cycle (EJC). Moreover, estimated power consumption of the automotive air conditioning system can be approximately reduced 20% under the conventional vapor compression cycle

Bio-oil synthesis from cassava pulp via hydrothermal liquefaction: Effects of catalysts and operating conditions

The influence of catalysts and operating conditions on the conversion and yield of bio-crude oil from CP via the hydrothermal liquefaction technique (HTL) were studied. HTL is commonly used to convert CP to bio-crude oil (BCO). Three independent factors—reaction temperatures (250–350 °C), reaction times (30–90 min), and CP concentrations (5–20 wt.%)—were investigated. Proximate analysis showed that CP comprises 84.61% volatile matter and 13.59% fixed carbon. The ultimate analysis demonstrated that CP has carbon and oxygen levels of 44.86% and 46.91%, respectively. Thermogravimetric analysis showed that CP begins to decompose at temperatures between 250–350 °C. The results show that KOH is the most suitable catalyst because it provides the highest BCO yield when compared to other catalysts under the same operating conditions. We found that the ideal operating conditions for maximizing BCO performance are 250 °C, pressure of 17.0 MPa, 90 min, 5 wt.%. Under these conditions, Fourier transforms infrared analysis showed that the most abundant chemical bonds found in BCO were CH3-O, CH3-C, and CH3. The findings of the CHNS analysis showed that BCO has an H/C ratio of 2.25, similar to that of petroleum and bio-diesel. Results from a gas chromatograph-mass spectrometer indicate that a fatty acid group is the main component of BCO

ผลของอุณหภูมิต่อพฤติกรรมของลำพุ่งน้ำมันสบู่ดำผสมน้ำมันดีเซลความเร็วสูง Effect of Test Chamber Temperature on High Speed Jatropha Oil Blends with Diesel Fuel Behaviors

บทคัดย่องานวิจัยนี้มีวัตถุประสงค์เพื่อศึกษาผลของอุณหภูมิที่มีต่อพฤติกรรมของลำพุ่งความเร็วสูงน้ำมันสบู่ดำผสมน้ำมันดีเซล การทดลองจะใช้น้ำมันสบู่ดำผสมกับน้ำมันดีเซลในอัตราส่วน 50:50 โดยปริมาตร ลำพุ่งกำเนิดด้วยวิธี Projectile Impact Driven (PID) ถูกฉีดเข้าไปในห้องทดสอบที่เปลี่ยนแปลงอุณหภูมิเป็น 30, 100 และ 150๐C พฤติกรรมของลำพุ่งและคลื่นกระแทกถูกบันทึกด้วยกล้องถ่ายภาพเคลื่อนไหวความเร็วสูงร่วมกับเทคนิคชาร์โดว์กราฟ จากการทดลองพบว่า อุณหภูมิมีผลกับความเร็วและพฤติกรรมของลำพุ่งน้ำมันสบู่ดำผสมแตกต่างกัน คือ ที่อุณหภูมิห้องทดสอบ 30, 100 และ 150๐C ความเร็วเริ่มต้นของลำพุ่งเป็น 1,600 m/s 800 m/s และ 1,400 m/s ตามลำดับ นอกจากนี้ยังพบว่าที่อุณหภูมิ 150๐C ลำพุ่งน้ำมันสบู่ดำผสมมีความเร็วเฉลี่ยสูงกว่ากรณีห้องทดสอบมีอุณหภูมิ 30๐C และ 100๐C เนื่องจากลำพุ่งน้ำมันสบู่ดำผสมเกิดการระเหย (atomization) ที่อุณหภูมิ 150๐CAbstractThe purpose of this research is to study effect of test chamber temperature on high speed jatropha oil blends with diesel fuel behaviors. In the experiment, jatropha oil blend with diesel fuel ratio of 50/50 by volume was used, the high speed liquid jets were generated by using the projectile impact driven (PID) method. The liquid jets were injected into the varied test chamber conditions at 30, 100 and 150๐C. The high speed liquid jets and shock wave behavior were recorded by the high speed video camera with shadowgraph technique.  From experimental results, it was found that at 30, 100 and 150๐C of test chamber temperatures the maximum velocity is around 1,600 m/s 800 m/s and 1,400 m/s, respectively. In addition, it was found that the liquid jet average velocity at 150๐C is much higher than that of 30๐C and 100๐C, because the atomization of jatropha oil blend was occurred at 150๐

รูปแบบสมรรถนะวิศวกรฝ่ายผลิตในอุตสาหกรรมยานยนต์และชิ้นส่วน กรณีศึกษานิคมอุตสาหกรรมอมตะซิตี้ระยอง

วารสารวิชาการและวิจัย มทร.พระนคร, 10 (1) : 114-126This research is aimed to developed and evaluate a competency model of production engineer in the automotive industry. The data is collected from Amata City Rayong. The research is performed with two steps: 1) create an engineering competency in the automotive industry using Delphi technique with 17 experts. Then 2) review the engineering competency with the focus group of management staffs from automotive industry in Amata City Rayong. The statistics used in the analysis were percentile, median and inter-quartile range. The results show that competency is consist of three parts. Part 1: management competency Part 2: functional competency Part 3: production engineering characteristic and consisted of four parts 1) the management of operational performance 2) production engineering 3) engineering knowledge 4) personal characteristics. Examining results in the competency model of production engineer in the automotive industry: the data is collected from Amata City Rayong created are appropriate and feasible in practice and performance as a performance model is built according to expert opinion.Rajamangala University of Technology Phra Nakho

Supersonic liquid diesel fuel jets : generation, shock wave characteristics, auto-ignition feasibilities

It is well known that high-speed liquid jetting is one of the most powerful techniquesavailable to cut or penetrate material. Recently, it has been conjecturedthat high-speed liquid jets may be beneficial in improving combustion in suchapplications as SCRAM jets and direct injection diesel engines. Although thereare practical limitations on maximum jet velocity, a fundamental study of thecharacteristics of high-speed liquid fuel jets and their auto-ignition feasibility isnecessary. Important benefits could be increased combustion efficiency and enhancedemission control from improved atomisation.The generation of high-speed liquid jets (water and diesel fuel) in the supersonicto hypersonic ranges by use of a vertical single stage powder gun isdescribed. The effect of the projectile velocity and projectile mass on the jet velocityis found experimentally. Jet exit velocities from a range of different nozzleinner profiles and nozzle hardness are thoroughly examined. The characteristicsand behaviour of the high-speed liquid jet and its leading bow shock wave havebeen studied with the aid of a shadowgraph technique. This provides a clearerpicture of each stage of the generation of hypersonic liquid jets. It makes possiblethe study of hypersonic diesel fuel jet characteristics and their potential forauto-ignition.The fundamental processes by which a supersonic liquid jet is generated byprojectile impact have been investigated. The momentum transfer from the projectileto the liquid and the shock wave reflection within the nozzle cavity are thekey items of interest. A new one-dimensional analysis has been used in order tosimplify this complex and difficult problem. The impact pressure obtained fromthe projectile was firstly derived. Then, an investigation of the intermittent pressureincrease in a closed end cavity and a simple stepped, cross-sectional nozzlewere carried out. The nozzle pressure and final jet velocity were estimated andcompared to a previous method and to experimental results. Some interestingcharacteristics found in the experiments relate well to those anticipated by theanalysis.The characteristics of a hypersonic diesel fuel jet and its leading edge shockwave were assessed for their potential for auto-ignition using fuel with cetanenumbers from 50-100. The investigations were performed at normal ambient airand at elevated air (110 ◦C) temperature. So far, there is no sign of auto-ignitionthat may occur because of the temperature rise of the induced shock