International Journal of Applied Technology Research (IJATR)
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Comparison of Utilization an Absorption and Vapour Compression Chiller in Sub-Tropical Country Building – A Feasibility Study
Full text linkThe present study investigate the feasibility of absorption chiller utilization as part of trigeneration system that possibly applied in sub-tropical country building. Trigeneration is refer to the heat utilisation from electric generator (combined heat and power, CHP) to generate absorption chiller in order to produce chilled water for air conditioning system (combined cooling, heat and power, CCHP). Compare to the vapour compression system, absorption chiller that is mainly generated by heat waste, promised benefit economically and environmentally. Overall efficiency of CCHP can reach 71 % and possibly reducing emission until 146709.07 kg CO2. Economic analysis using the Payback period methodology has shown that the CCHP would produce a return on investment of 2.6 years. Improvements absorption chiller and support from government are expected to lead to increased return on investment and improved viability of the system
The Pyrolysis Reactor Design and The Effect of Liquid Smoke from Coconut Shell on Microbial Contamination of Tofu
Full text linkLiquid smoke is a natural food preservative which can be made of coconut shells through the pyrolysis process. This study aimed to design a pyrolysis reactor and utilize the coconut shell waste to produce liquid smoke as a natural preservative of tofu. 1.5 kg of chopped coconut shell was pyrolyzed at 400C for 5 hours and produced 488 mL of grade 3 liquid smoke with a yield of 34.23%. The liquid smoke was then purified by extraction using ethyl acetate (1: 1 ratio) solvent and 70C temperature for 2 hours. The extract was then distilled at 80C and produced grade 1 liquid smoke. This liquid smoke had an acid content of 12.26% and a phenol content of 0.73%. This liquid smoke was then applied to tofu for 3 days and analyzed the microbial contamination. The smallest amount of microbial contamination was found in the samples of yellow tofu and white tofu coated with liquid smoke and stored in the refrigerator for 1.4 × 105 CFU / mL and 8 × 103 CFU/ml
Design of Phase-Shifting Transformer Based on Simulink Matlab Simulation
Full text linkUsing variable speed drive for controlling speed of three-phase induction motor in industrial sector gives an advantage of reducing consumption of electrical energy; on the other hand, it also causes a disadvantage of source current harmonic. To solve the problem of source current harmonic, a method of using phase-shifting transformer is applied. This method may be applied in a system with two VSDs or more connected to a three-phase power supply. The application of this phase-shifting transformer method could be as simple as using of two transformer with Y-y (wye-wye) and Y-d (wye-delta) three-phase winding connections to give a phase-shifting of 30 or more complex as it uses two transformer with Y-y and Y-z (wye-zigzag) three-phase winding connections to give a phase-shifting less than 30. This paper proposes design of five different phase-shifting transformer configurations to produce 30, 20, 15, 12 and 10 phase-shifting. Simulation on a computer-based software, Simulink Matlab, then confirmed that the proposed phase-shifting transformer design gives a very accurate result regarding to phase-shifting and magnitudes of input and output voltage of the phase-shifting transformers
Manufacturing Process beyond Conventional Plasticity Theory: Case Study in Manufacturing Low Spring Index Coil
Full text linkIn the academic world, conventional plasticity theory limits the cold process due to energy inefficiency, material properties and residual stress that may inhibit the quality of a product, and therefore usually not recommended. However, industrial competition pushes that limits against the edge. Knowing the consequences in advance helps reducing the damage that may have been caused by such a violation. This paper shows an example in the form of a case study. A coil spring with a very low spring index that academically suggested to be made using hot process was attempted to be manufactured using cold coiling machine. The case study shows that although it is possible, extra careful and timely handling must be done to successfully manufacture it. A coil with excessive residual stress is shown in this paper. That residual stress alone was capable in damaging the coil during manufacturing. The defect takes place after coiling and before tempering process. A fracture mechanics was used to analyze the failure, which is the splitting due to excessive residual stress. The case study also shows that the problem can be solved by speedy and subsequent stress relieve annealing process
The Harmonics Effect of Variable Speed Drives on Generator Performance
Full text linkLarge motors often burden synchronous generators as power plants in factories. This motor is commonly using to regulate rotation using Variable Speed Drive (VSD). From the load side, VSD, as a regulator of motor rotation, can reduce power loss. On the generator side as a power plant, this load with VSD affects the waveform of the generator. The experiments on a small capacity generator (6 kVA) with a VSD as regulating the motor rotation with a load of about 1.1 kW shows effectiveness power transfer is about 40.7% with VSD, and without VSD, efficiency is approximately 39.6%. The motor losses by installing VSD interpreted as transferring losses to the generator with savings is about 1 %. The experiments also showed that generator performance decreases when loaded with VSD at around 6%, and a generator temperature increases at 20 0C higher than without VSD