Performance of Al2O3-SiO2/PAG employed composite nanolubricant in automotive air conditioning (AAC) system

Automotive Air conditioning (AAC) system is the contributor of harmful gasses emission and global warming. In order to solve the issues, investigation on potential improvement in lubrication used in air conditioning system is done to improve the system performance and efficiency. The performance of AAC system namely cooling capacity, compressor work, coefficient of performance (COP) and power consumption was investigated by comparing pure lubricant and Al2O3-SiO2/PAG nanolubricants. Performance of AAC by using different ranges of refrigerant charges (95 to 155 g) and speeds (1200 and 1800 rpm) was investigated. The result shows that the cooling capacity and COP of pure lubricant were relatively lower than Al2O3-SiO2/PAG nanolubricants. The compressor work and power consumptions of Al2O3-SiO2/PAG nanolubricants were greatly reduced. Cooling capacity and COP are enhanced by 102.99% and 23% respectively. The compressor work and power consumption are reduced by 25.9% and 28.24% respectively. From the results, nanolubricants gives more advantages in AAC performance over pure lubricant. Therefore, Al2O3-SiO2/PAG composite nanolubricants is recommended to be used as the compressor lubrication to enhance AAC performances system

Effects of indoor air quality on the occupant's health and productivity in an office building

Indoor Air Quality (IAQ) is an important parameter in deciding the status of Sick Bulding Syndrome (SBS). Poor IAQ which leads to SBS can result in adverse effect on the health of the occupant which causing lower productivity. This study was conducted to establish correlation between IAQ and employee’s productivity. Five parameters of IAQ which include air velocity, air temperature, relative humidity, particulate matters ≥ 0.3 μm and CO2 were considered in this study. The values of these parameters were measured using Davis Anemometer, Particle Counter GT 521 and YES Plus LGA Meter. The measured data were then used as an input data for simulation model of the room using Comsol Multiphysics software. The simulation generated the indoor air velocity of the room and particle distribution. For validation purpose, only the predicted velocity was compared with the measured value, and found that the percentage difference were in the range of 1.5% to 8.45% (below than 10%). Once the model had been validated, the parametric study of air supply inlet position was conducted on the model and found that the position of air supply inlet with x = 2.5 ft, y = 10 ft and H = 6.5 ft give the most efficient air distribution model for diluting the impurities due to the particulate. The questionnaire survey distributed amongst the occupants of the room showed that the occupants were less satisfied (75%) with the IAQ which can lead to SBS problem. The analysis of correlation between IAQ and occupant's productivity depicted that both of the factors were correlated with Rank-Spearman value of 0.648. This study serves as a good platform in assessing IAQ based on the modelling and simulation approach

Compressibility and permeability of solidified dredged marine soils (DMS) with the addition of cement andor waste granular materials (WGM)

Dredged marine soils that obtained from dredging work were characterize as geo-waste, which is prone to be dumped rather than to be reused. This type of soil is high in compressibility and low in load bearing capacity. The engineering properties of this soft soil can be improve via soil solidification method. Cement is the common hydraulic binder used in soil solidification, were found to generate the emission of greenhouse gasses (GHG), particularly carbon dioxide (CO2) which also had affected the earth’s atmosphere. Therefore, there has been an increasing interest in using alternate pozzolanic materials such as waste granular materials (WGM) to fully or partially substituted the use of cement in soil solidification. WGM such as coal bottom ash (BA) and palm oil clinker (POC) were opted due to its pozzolanic properties. Prior to the planning of reclamation work using DMS admixed with conventional and/or alternate pozzolanic materials, the consolidation characteristics of the admixed materials must be acknowledged. Hence, the present study will examine the amount of settlement and coefficient of permeability (k) of DMS treated with cement and/or WGM in laboratory-scale experiments. Samples were prepared in various proportion in order to examine the individual effect of the cement and/or alternate pozzolanic materials on compressibility and permeability. For cement-admixed DMS, sample with 20 % of cement have significantly reduced the settlement than untreated and 10 % cemented DMS. For WGM-admixed DMS, the initial void ratio is low as compared to the untreated DMS due to the rearrangement of soil particles, which is densely packed. For cement-WGM-admixed DMS, samples of 15C50BA and 15C50POC displayed significant settlement reduction than 10C100BA, 10C100POC and untreated samples

Air Quality Study at Different Elevation Levels Using Drone Payload Air Quality Measurement Device (D-PAQ)

Construction sites can be found in both urban and rural areas, often in close proximity to residences. They can thus cause home pollution due to the distance and the materials used. This study aims to visualize PM2.5, PM10, temperature and humidity by producing air quality mapping and correlating parameters at the stadium and construction site. An Arduino-based air quality measurement payload device was developed to measure the air quality by different levels. The drone was used to collect air quality data by mounting the device to the drone. Measurements were taken at three different elevations for each study area, and the application software generates the air quality map based on the location coordinates. The correlation evaluation of the concentration of PM2.5 and PM10 with temperature and humidity was then determined. The results showed that the concentrations of PM2.5 and PM10 at the construction site are much higher compared to the stadium due to the construction activities nearby. Keywords: air quality, unmanned aerial vehicle, mappin

Autocorrelated process control: Geometric Brownian Motion approach versus Box-Jenkins approach

Existing of autocorrelation will bring a significant effect on the performance and accuracy of process control if the problem does not handle carefully. When dealing with autocorrelated process, Box-Jenkins method will be preferred because of the popularity. However, the computation of Box-Jenkins method is too complicated and challenging which cause of time-consuming. Therefore, an alternative method which known as Geometric Brownian Motion (GBM) is introduced to monitor the autocorrelated process. One real case of furnace temperature data is conducted to compare the performance of Box-Jenkins and GBM methods in monitoring autocorrelation process. Both methods give the same results in terms of model accuracy and monitoring process control. Yet, GBM is superior compared to Box-Jenkins method due to its simplicity and practically with shorter computational time

Determining significant parameters on health and well-being of building occupants towards re-engineered inclusive environment

People spend over 90% of their time in the buildings. A building is a place where people are spending more time doing activities, thus an inclusive environment of the buildings is very important to ensure that people are having a healthy life. An inclusive environment is important for the well-being of building occupants. Indoor environmental quality is one of the essential elements in creating an inclusive environment in which a poor quality of indoor environment affects the health of the occupants both physically and mentally, their performance, productivity, comfort, satisfaction, and well-being. Even though people are towards creating an inclusive environment but it is a limited study on the parameters of the inclusive environment. Thus, this paper is to study the parameters of the inclusive environment by focused on the element of the indoor environmental quality for building occupants based on literature reviews of articles between the year 2006 and 2016. Based on the content analysis, it has been discovered that there are various parameters of an inclusive environment which are visual comfort, thermal comfort, acoustic comfort, indoor air quality, buildings factors, occupants’ factors, and climate condition factors. The parameters can be very useful as guidelines and development of policy in providing inclusive environment for the healthy lifestyle of building occupants

Improvement of Nanofluid stability using 4-Step UV-Vis Spectral Absorbency Analysis / M.Z. Sharif...[et al.]

The most challenging matters for the utilization of nanofluid into a certain system is its stability. The nanofluid with undesirable stability will damage the system due to fouling, and settlement from the base fluid. In addition, unstable nanofluid will have a lower thermal performance enhancement. An improved method, 4-Step UV-Vis spectral absorbency analysis has been suggested to improve the stability of the nanofluid. SiO2 nanoparticles were dispersed in the PAG lubricant by using the two-step preparation method. The stabilization methods of the SiO2/PAG were done by using the suggested method. The result indicates that all nanofluid shows good stability in stationary position even after 30 days. The absorbance of every three concentration decreased compared to their respective initial absorbance, but maintained for specific value at over 70 % compared to the initial absorbance even after 30 days

Determining significant parameters on health and well-being of building occupants towards re-engineered inclusive environment

People spend over 90% of their time in the buildings. A building is a place where people are spending more time doing activities, thus an inclusive environment of the buildings is very important to ensure that people are having a healthy life. An inclusive environment is important for the well-being of building occupants. Indoor environmental quality is one of the essential elements in creating an inclusive environment in which a poor quality of indoor environment affects the health of the occupants both physically and mentally, their performance, productivity, comfort, satisfaction, and well-being. Even though people are towards creating an inclusive environment but it is a limited study on the parameters of the inclusive environment. Thus, this paper is to study the parameters of the inclusive environment by focused on the element of the indoor environmental quality for building occupants based on literature reviews of articles between the year 2006 and 2016. Based on the content analysis, it has been discovered that there are various parameters of an inclusive environment which are visual comfort, thermal comfort, acoustic comfort, indoor air quality, buildings factors, occupants’ factors, and climate condition factors. The parameters can be very useful as guidelines and development of policy in providing inclusive environment for the healthy lifestyle of building occupants

A Tribological Analysis of PAO-Based Hybrid SiO2-TiO2 Nanolubricants

Friction and wear are caused by contact between sliding surfaces over time. It is possible to reduce friction in a compressor by improving its lubrication. The nanoparticle lubrication will aid in reducing wear and friction of the piston mechanism of the compressor. This work aims to analyse the tribology properties of performance of the system employing Polyalphaolefin (PAO)-based hybrid nanolubricants. A two-step method was used to disperse SiO2 and TiO2 nanoparticles in the PAO lubricant at volume concentrations of 0.01% and 0.05% using a two-step method. Then, hybrid nanolubricants are observed visually, and their coefficient of friction (COF) is evaluated using a four-ball tribometer. The SiO2-TiO2/PAO hybrid nanolubricants were found to have a higher than 80% sedimentation ratio up to 180 hours and to be visually stable for up to 30 days. The 0.01% SiO2-TiO2/PAO has a lower COF than the base PAO 68 oil. The 0.05%, however, does not show the expected reduction. The COF ratio for volume concentrations of 0.01% and 0.05% is 0.97 and 1.01, respectively. The highest COF reduction of nanolubricants was attained up to 2.53% at 0.01% volume concentration. Therefore, 0.01% SiO2-TiO2/PAO is the ideal condition for use and is recommended for further investigations

Tribology performance of TiO2-SiO2/PVE nanolubricant at various binary ratios for the automotive air-conditioning system

Tribological properties are crucial for air-conditioning system performance. The properties can be improved using nanolubricant. However, the effect of the binary ratio of hybrid nanolubricants on the tribological performance of automotive systems is limited in the literature. Therefore, the present study investigates the tribology performance of TiO2-SiO2 nanolubricants for application in automotive air-conditioning (AAC) systems. The dispersion of TiO2 and SiO2 into PVE lubricant was carried out using a two-step method. Subsequently, the dispersion stability was assessed ualitatively and quantitatively. The samples were characterised by a volume concentration of 0.010%, with variations in the mixture ratio of 20:80, 40:60, 50:50, 60:40, and 80:20. Coefficient of friction (COF) and wear scar diameter (WSD) values were determined using the Koehler Four ball Tribo Tester and Light Compound Microscopy. The investigation revealed that each sample experienced a reduction in COF, with the 40:60 ratio demonstrating the best ratio with the most significant decrease of 37.09%. At the same time, the COF decreased by 8.34%, 2.12%, 7.37%, and 15.11% for the nanolubricant samples at 20:80, 50:50, 60:40, and 80:20, respectively. The WSD evaluation showed that the 40:60 ratio has the lowest scar diameter of 0.0344 mm and a 37.09% wear rate decrease compared to pure lubricant. Each sample exhibits superior performance when evaluated for tribological characteristics and performance, particularly in the case of nanolubricants with the 40:60 ratio. The TiO2-SiO2/PVE, characterised by a volume concentration of 0.010%, has remarkable efficacy across different binary ratios, making it highly recommended with a 40:60 ratio for lubricating AAC compressor systems