PI control application for building air conditioning system

This manuscript presents a PI controller implementation to control the compressor speed of an air conditioning system based on cooling load to fulfill thermal comfort requirements with higher energy efficiency. Hence, an interface was designed to monitor the experiment, including the controller algorithm. The temperature settings of the conditioned space were 20, 22, and 24oC with internal heat loads of 0 and 1000 W. The experiments conducted indicated that the proposed technique had better temperature control and energy efficiency compared to the thermostat controller

Single-cylinder 125 CC stepped piston engine for mobility and portable power generation applications

Two-stroke engines is far simpler than four-stroke version from its physical perspective. For a given brake output, two-stroke is lighter, easier to work on, and provide higher power-to-weight ratio than the four-stroke, making it suitable for small platform applications. However a conventional two-stroke engine has a reputation for generating smoke and unburned fuel, a situation which does not meet many emissions regulations, now enforced around the world. Thus for many decades two-stroke engines were not favored, giving ways to four-stroke engines to dominate applications, especially for mobile power-generation purposes. In the quest to improve the potential of such an engine, a group of researchers from the Automotive Development Centre (ADC), Universiti Teknologi Malaysia (UTM) has come up with a 125 cc, air-cooled stepped-piston engine to demonstrate the higher power-to-weight ratio feature, apart from overcoming emission reduction. The engine is designed to mitigate the problem of mixture short circuiting, which is the major hindrance to combustion efficiency, and for this to happen they have incorporated a three-port stratification strategy onto the engine. This paper provides the overview related to the earlier work done to infuse the necessary features and highlights some of the performance features of this unique engine design

The effect of decontaminants on vehicle cooling system

This study analyzed the performance of the water pump and radiator under process of as-it-is condition, contamination, and decontamination among three types of radiator, namely used, new, and new coated radiators. Contamination process is completed by spraying the mixture of fine clay and water onto the radiator’s surface for 30 layers Decontamination process is done by AirestecSdnBhd, a local company. Internal analysis covers replacing the cooling fluid with used radiator water, tap water and tap water with additive to run experiments. As result, water pump displays similar trends for each set of experiment and air flow velocity, and its highest efficiency is 8.20 %. For external treatment, the effectiveness after decontamination process for new coated radiator, new radiator and used radiator are 43.60%, 31.42% and 30.16% respectively. While for internal treatment, tap water with additive, tap water and used radiator water exhibits 31.79%, 31.42% and 28.98% of effectiveness. As a conclusion, decontaminants towards radiator are effective to increase the performance of the radiator, but no impact on the efficiency of the water pump.For internal treatment, cooling fluid with additive help enhance the radiator performance in cooling system

Comparison of air to air and air to water intercoolers in the cooling process of a turbocharger engine

Compressed air from a turbocharger needs to be cooled down to prevent knocking inside the combustion chamber from occurring. In the present study, air to water intercooler is used as a heat exchanger to minimize the temperature rise of the charged air produced from the turbocharger i.e. water is used as the medium for cooling the temperature of the charged air before the intake manifold instead of using direct air, which is the common medium of any intercooling system. The experiments were conducted with engine speeds of 2000, 2500, 3000, 3500, 4000, 4500 and 5000 rpm, with pressure of 0.6, 0.8 and 1.0 bar. The present study found that the air to water intercooler is more efficient and the heat transfer is much better than that of the air to air intercooler. This is due to the air flow to the water inside the intercooler is better compared to the system that uses an air to air intercooler system

Performance and emission evaluations of a prototype stepped-piston engine using carburetor and direct fuel-injection systems

Two-stroke engines have been used for sometimes in automotive and stationary applications since early 20th century. The advantages of two-stroke engines are obvious, i.e., lighter, simpler and less expensive to manufacture. Technically, two-stroke engines have the potential to pack almost twice the power into the same space because there are twice as many power strokes per revolution. The combination of lightweight and twice the power gives two-stroke engines a great power-to-weight ratio compared to many four stroke engine designs. However due to the short-circuiting process of the fuel before combustion, this has resulted in deterioration in overall performances especially poor combustion efficiency and high white smoke emission problem. Coupled with the improvement in the four-stroke engine technology, the former has overcome the latter in being the choice for mobile platform applications. Due to high fuel cost and the need to explore the use of other fuel sources, notably gaseous fuels, a number of enthusiasts and engine developers have revisited the two-stroke engine design. Fuels such as hydrogen and methane are said to be ideal for use with the incorporation of the some new features (Goldsborough and Blaringan, 2003). An engine design and development program was initiated at Universiti Teknologi Malaysia (UTM) in year 2003 to develop local R&D capabilities in small power-train engineering. The exercise evolved around the development of an air-cooled single cylinder of stepped-piston engine concept. The term “stepped piston” refers to the conventional piston having compounded with a larger diameter section at the rear section of its geometry. The changes to the original design were made as the research group feels that there are rooms for improvements. In addition to this, the modifications will infuse other innovative scope of work from design to product testing activities (Hooper, 1985).This program, eventually leads to the incorporation of features, is expected to enhance performance of the prototype and subsequently exhaust emission. This is in anticipation of producing a working prototype for multiple applications namely stationary and automotive. The gasoline stepped-piston engine is a relatively new design concept for small mobile power plants. It is an engine, operating on a two-stroke cycle but is infused with four-stroke engine features. It has a build-in supercharger mechanism (by virtue of the extended flange) that improves the scavenging process thus improve combustion efficiency. Due to these operating characteristics, the engine has all the attributes of a low emission, high-efficiency power plant that eliminates many of the major weaknesses associated with the Otto four-stroke engine and with modern two-stroke engines

Investigation of cylinder deactivation strategies for better fuel consumption using 1-D simulation method

In order to meet consumer and legislation requirements, big investments on key technology strategies have been made to ensure fuel consumption is reduced. Recent technologies for gasoline engines are lean combustion technologies (including direct injection and homogenous charged compression ignition), optimizing intake and exhaust valve timing with valve lift and also cylinder deactivation system (CDA) have been practised to improve the engine efficiency. In this study, the purpose is to investigate the engine behaviour when running at different cylinder deactivation (CDA) strategies. One-dimensional engine model software called GT-Power is used to predict the engine performances. There are total of five strategies that have been studied which include normal mode, spark plug off mode, cylinder deactivation mode, intake normal with exhaust off mode, and intake off with exhaust normal mode. Engine performance outputs of each strategy are predicted and compared at BMEP of 3 bars with engine speed of 2500 rpm. Also, the effect of CDA strategies on in-cylinder pressure and pumping loss are performed. The study shows that all of these cylinder deactivation strategies are significantly reduce the pumping loss (PMEP) and fuel consumption, furthermore increasing the thermal efficiency of the engine. The results suggest that the most beneficial strategy for activating CDA is for the case whereby both the intake and exhaust valves are kept closed. This strategy successfully reduced the BSFC. It found that most of these cylinder deactivation strategies improve the engine performance during part load engine condition

The effect of bio-based additives on engine performance and emissions of petrol and diesel engine

Fuel additives are additives that are added to fuel in small quantities to give improvement in terms of engine performance and emissions. Aftermarket fuel additives can be divided into two, chemical-based and bio-based. In this project, the effect of bio-based fuel additives on engine performance and exhaust emissions of a petrol and diesel engine is studied. The blending ratio is developed based on the instruction given on the bottle of the additives. The ratio of the fuel additives used for Vivo Racing (VR) is between 0.21% and 0.25%, Vivo Flawless (VF) is between 0.10% and 0.14% and Diesel Energy is between 0.14% and 0.18%. Constant throttle test had been done on both petrol and diesel engine. The results show that the fuel additives reduce brake power and brake specific fuel consumption while increasing brake thermal efficiency and reducing exhaust emissions. For brake power, VR0.24 is the best. For brake specific fuel consumption, the best are VR0.23 and VF0.11 for petrol and diesel engine respectively. For brake thermal efficiency, the best are VR0.24 and DE0.17. For HC composition, the lowest are VR0.25 and DE0.17. For CO composition, VR0.22 and DE0.14 are the lowest. As for NOx, the lowest are VR0.25 and DE0.17

Development of palm biomass briquettes with polyethylene plastic waste addition

High global energy demand scenario has driven towards transformation from sole dependence on fossil fuels to utilization of inexhaustible renewable energy sources such as hydro, biomass, solar and wind. Renewable energy sources are abundant in Malaysia, especially palm biomass residues that are produced during the oil extraction process of fresh fruit bunch. Therefore, it is inevitable to harness these bioenergy sources, in order to prevent waste accumulation at adjacent to palm mills. Briquetting of palm biomass such as empty fruit bunch (EFB) with polyethylene (PE) plastics waste addition is expected not only could maximize the utilization of energy resources, but also could become as a potential solution for residue and municipal plastics waste disposal. In the present study, the physical and combustion properties of palm biomass briquettes that contain novel mixture of pulverized EFB and PE plastics waste were investigated experimentally. The briquettes were produced with different mixing ratio of EFB and PE plastics (weight ratios of 95:5, 90:10 and 85:15), under various heating temperatures (130-190°C) and at constant compaction pressure of 7 MPa. Based on the results, it can be said that heating temperature plays a significant role in affecting physical properties such as relaxed density and compressive strength. The values of relaxed density and compressive strength are within the range of 1100 to 1300 kg/m3 and 0.8 to 1.2 MPa, respectively. Meanwhile, mixing ratio does affect relaxed density and gross calorific value. All values of gross calorific (17900 to 21000 kJ/kg) and moisture content (7% to 9%) are found to fulfill the requirement for commercialization as stated by DIN51731 (gross calorific value>17500 kJ/kg and moisture content<10%). Even though the values of ash content (3% to 4%) exceed the limitation as stated by the standard (<0.7%), it is still considered very competitive if compared to the commonly used local briquette that contains mesocarp fibre and shell (5.8%). Finally, it can be concluded that the best quality of briquette can be achieved when highest composition of PE plastics (weight percentage of 15%) is used and the briquetting process is performed at the highest temperature (190℃)

POSSIBLE IMPACT OF THE LATEST INTERNATIONAL STANDARD OF AUDITING 570 ON THE RATE OF GOING CONCERN OPINION ISSUANCE IN MALAYSIA

The problem that Malaysian auditors do not issue going concern opinion (GC opinion) to seriously financially distressed companies is still a pressing issue. The latest International Standards on Auditing 570 Going Concern (ISA 570) has been released and made effective in Malaysia starting from 15th December 2016. It is reasonable to expect that the new ISA 570 (2016) could at least reduce the incidence of Malaysian auditors do not want to issue GC opinion to financially distress companies. Overall, we are in the opinion that there is no strong ground to expect the new ISA (2016) can reduce the problem of Malaysian auditor do not issue GC opinion to a very large percentage of seriously financially distress companies. This is because there is no new stricter measure has been introduced in the latest ISA 570 (2016). However, Malaysian policy makers and standard setters still have at least four measures if they want to improve the rate and practice of GC opinion issuance in this country. Researchers on the other hand should examine the effectiveness of the new ISA 570 (2016), at least

Possible impact of the latest international standard of auditing 570 on the rate of going concern opinion issuance in Malaysia

The problem that Malaysian auditors do not issue going concern opinion (GC opinion) to seriously financially distressed companies is still a pressing issue. The latest International Standards on Auditing 570 Going Concern (ISA 570) has been released and made effective in Malaysia starting from 15th December 2016. It is reasonable to expect that the new ISA 570 (2016) could at least reduce the incidence of Malaysian auditors do not want to issue GC opinion to financially distress companies. Overall, we are in the opinion that there is no strong ground to expect the new ISA (2016) can reduce the problem of Malaysian auditor do not issue GC opinion to a very large percentage of seriously financially distress companies. This is because there is no new stricter measure has been introduced in the latest ISA 570 (2016). However, Malaysian policy makers and standard setters still have at least four measures if they want to improve the rate and practice of GC opinion issuance in this country. Researchers on the other hand should examine the effectiveness of the new ISA 570 (2016), at least