Yusoff Ali

Evaluation Of Adding Flash Tank To Solar Combined Ejector–Absorption Refrigeration System

Performance of the absorption cooling system is still a challenge due to the coefficient of performance (COP) that is generally poor when compared with the conventional vapor compression cycle. High solar radiation in hot climates is usually associated with high ambient temperature and consequently peak cooling demand. Absorption cooling cycles can be powered by solar but the performance is limited by heat source temperature (solar collector) and high ambient temperature that can affect the condensation process. Efficiency enhancement of the system components is essential to increase the COP of the system. A modification in the combined absorption–ejector cooling system is adopted. Adding a removable flash tank between the condenser and evaporator could improve entrainment ratio of the ejector, along with improving the cooling effect inside the evaporator. A computer simulation program is developed to evaluate the performance of the modified combined cycle using aqua-ammonia (NH3–H2O) refrigerant. The performance of the proposed combined cooling cycle is compared with basic absorption, and combined absorption–ejector cooling cycles. Results showed a significant improvement in the COP of the modified cycle at different operating conditions. Cooling effect and capacity of the evaporator is enhanced due to the reduction of flash gas delivered to the evaporator. Furthermore, the flash tank optimized the ejector entertainment ratio and consequently increasing the condenser pressure. This optimization will enable the system to perform well in hot climates where the condenser efficiency is limited by ambient temperature.

The Effect of Injection Timings on Performance and Emissions of Compressed Natural-Gas Direct Injection Engine

This experimental part investigates the effect of injection timing on performance and emissions of homogenous mixture compressed natural-gas direct injection. The engine of 1.6 L capacity, 4 cylinders, spark ignition, and compression ratio of 14 was used. Performance and emission were recorded under wide-open throttle using an engine control system (Rotronics) and the portable exhaust gas analyser (Kane). The engine was tested at speed ranging from 1500 revolutions per minute (RPM) to 4000 RPM with 500 RPM increments. The engine control unit (ECU) was modified using Motec 800. The injection timings investigated were at the end of injection (EOI) 120 bTDC, 180 bTDC, 300 bTDC, and 360 bTDC. Results show high brake power, torque, and BMEP with 120 as compared with the other injection timings. At 4000 RPM the power, torque, and BMEP with 120 were 5% compared to that with 180. Furthermore, it shows low BSFC and high fuel conversion efficiency with 120. With 360, the engine produced less CO and CO2 at higher speeds.

The impact on quality of students through participation in international challenge project - a case study on UKM's students

A survey was conducted to find the impact of quality of students and the experience gained through international challenges outdoor project activities which involved the students of the UKM. The survey was done on the students that participated in the Shell Eco Marathon which was first organized in Malaysia and in Asia region. The objective is to find out whether the students have acquired creativity, self confidence, team work, good management and good communication through project and how the students work in team in achieving the goals of the project. This brief analysis of the survey has shown that the response of the students on quality of good management, good communication and teamwork. There is some indication that project outdoor sports activities have create effective way to poster good management and communication among the team. However, on creativity and innovative thinking, the students have not acquired full creativity and innovative idea on transferring the academic knowledge applied into the project. The hard working effort has created integration among some races Malays and Chinese but the participation of Indian need to be improved. Various qualities, such as cooperation, the self confidence, yearning to be the champion and good leadership were discovered. The hard working effort and high commitment has been shown by the students to work together and having good leadership, good management and good communication. The creativity of the group is still need improvement. This survey has also shown that the project generates healthy understanding amongst students, for integration and exchanges of views for environmental conservation and future sustainable of human life in this region as well as in the whole world. The result of the survey clearly support the positive thinking of the students to demonstrate the good management and good communication amongst the group member and that what takes them to be successful in real life.

The effect of spray angles of the injector on the power of compressed natural gas direct injection (CNGDI) engine

A study was carried out on the new design of fuel injectors for Compressed Natural Gas Direct Injection (CNGDI) engine. There are two injectors designed with 30° and 70° spray angle was developed and tested. The tests on the injectors were carried out using Single Cylinder Research Engine SCRE with compression ratio of 14:1. The SCRE test bed used computerized data acquisition system. There are two main parameters for the selection of the best injector i.e. the spray angle (30° and 70°) and the operating pressure is set at 2.0 MPa. From the study, the engine performance and the emission were recorded from the test. The results indicated that the injector with 70° spray angle achieved higher performance than the other injector.

Development of CNG direct injection (CNGDI) clean fuel system for extra power in small engine

A new design of fuel system for CNG engine with direct injection (CNGDI) was developed for a demonstration project. The development of the fuel system was done on the engine with cylinder head modifications, for fuel injector and spark plug openings included in the new cylinder head. The piston was also redesigned for higher compression ratio. The fuel rails and the regulators are also designed for the direct injection system operating at higher pressure about 2.0 MPa. The control of the injection timing for the direct injectors are also controlled by the Electronic Control Unit specially designed for DI by another group project. The injectors are selected after testing with the various injection pressures and spray angles. For the best performance of the high-pressure system, selection is made from the tests on single cylinder research engine (SCRE). The components in the fuel system have to be of higher quality and complied with codes and standards to secure the safety of engine for high-pressure operat...