Eflita Yohana

Induction Hardening of Carbon Steel Material: The Effect of Specimen Diameter

Induction hardening is well developed technology in many industrial applications, e.g. automotive, tool manufacturing, casting technology, sheet metal forming etc. The surface hardened medium carbon steels are widely used for critical automotive and machine components such as propulsion shafts, crankshafts and steering knuckles which require high fatigue resistance. However, some of small and medium sized enterprises, focused in metal manufacturing in Indonesia have not complete practical knowledge in employing induction hardening to harden the mechanical components. This paper present a technical report of induction hardening process for medium carbon steel material with considering the effect of specimen diameter. The results show that the increase of the specimen diameter increases the current input requirement which also increase the power requirement as a consequence. The induction frequency is automatically decrease when the specimen diameter is increase and resulted in the deeper hardening layer on the surface. The hardness layer of specimen A ranges from outer surface to 6 mm from the surface whereas specimen B ranges from outer surface to 10 mm from the surface from. The micro structure evolution from the surface to the center of the specimen for the both specimen is almost similar. It is mostly affected by the heating temperature and heat distribution from the surface to the center of specimen.

Effect of immobile isolated enzymes from rumen liquid by using alginate matrices on the bay leaf extraction

This research aims to develop the enzymatically of bay leaves phytochemical extraction process. The novelty and the main innovations of this research is the development of extraction process by using enzymatic extractor and isolate the enzymes from rumen liquid to shift the equilibrium phase, increase the extraction rate and increase the extraction yield. The activity of rumen liquid enzyme was represented by the activity of cellulase and protease. The analyze of total flavonoid content was performed by using UV-Vis Spectrofometry. The activity of immobilized enzyme of cellulase (0.08±0.00 U/ml) was lower than the un-immobilized one (0.23±0.00 U/ml). However, there was no difference activity of the immobilized (0.75±0.00 U/ml) and un-immobilized (0.76±0.01 U/ml) of protease. The model of mass transfer of un-immobilized enzyme can be fitted on the experimental data, however the model of mass transfer of immobilized enzyme did not match with the experimental data. The mass transfer coefficient of enzymatic extraction flavonoids bay leaf without immobilization was 0.17167 s−1 which greater than the reported value of obtained KLa from extraction by using electric heating.This research aims to develop the enzymatically of bay leaves phytochemical extraction process. The novelty and the main innovations of this research is the development of extraction process by using enzymatic extractor and isolate the enzymes from rumen liquid to shift the equilibrium phase, increase the extraction rate and increase the extraction yield. The activity of rumen liquid enzyme was represented by the activity of cellulase and protease. The analyze of total flavonoid content was performed by using UV-Vis Spectrofometry. The activity of immobilized enzyme of cellulase (0.08±0.00 U/ml) was lower than the un-immobilized one (0.23±0.00 U/ml). However, there was no difference activity of the immobilized (0.75±0.00 U/ml) and un-immobilized (0.76±0.01 U/ml) of protease. The model of mass transfer of un-immobilized enzyme can be fitted on the experimental data, however the model of mass transfer of immobilized enzyme did not match with the experimental data. The mass transfer coefficient of enzymatic ...

Preparation and characterization of oil palm shell activated carbon by alkali chemical activation method

As an excellent and versatile adsorbent, activated carbon is widely used for a number of applications on an industrial sector due to its numerous unique characteristics. Nowadays, inexpensive and effective alternatives to the existing commercial activated carbon have been a focus of many studies. Oil palm shell is one of the potential precursor materials for activated carbon production due to its high carbon content. Among the chemical activation agents commonly used in the activation process, alkaline hydroxides have recently been a great interest since the production of highly developed porosity activated carbons. In this study, oil palm activated carbon was prepared by NaOH impregnation and followed by carbonization at temperatures of 400°C and 500°C. The oil palm shell was impregnated with 1% of NaOH solution for 24 hours at room temperature. The filtration residue was then oven dried at 60°C for five hour. The dried oil palm shell was then crushed, grinded and subjected to the pyrolysis apparatus. The pyrolysis was conducted at two different temperatures, i.e. 400°C and 500°C for five hours. The activated carbon was then analyzed based on Indonesia’s industrial standard for activated carbon. The research showed that the yield of activated carbon decreases with the increasing of the carbonization temperature due to the loss of most of the volatile matter at a higher temperature. Furthermore, it showed that the moisture content, ash content, and Iod number fulfill the Indonesian Industrial Standard (SII no. 0258-79). Meanwhile, the volatile matter content and the fixed carbon content are out of the SII criteria.As an excellent and versatile adsorbent, activated carbon is widely used for a number of applications on an industrial sector due to its numerous unique characteristics. Nowadays, inexpensive and effective alternatives to the existing commercial activated carbon have been a focus of many studies. Oil palm shell is one of the potential precursor materials for activated carbon production due to its high carbon content. Among the chemical activation agents commonly used in the activation process, alkaline hydroxides have recently been a great interest since the production of highly developed porosity activated carbons. In this study, oil palm activated carbon was prepared by NaOH impregnation and followed by carbonization at temperatures of 400°C and 500°C. The oil palm shell was impregnated with 1% of NaOH solution for 24 hours at room temperature. The filtration residue was then oven dried at 60°C for five hour. The dried oil palm shell was then crushed, grinded and subjected to the pyrolysis apparatus. Th...

A study of tea leaves drying using dehumidification process and regeneration of liquid desiccant in a closed-cycle dehumidification-humidification

Tea plants in Indonesia are derived from Carmelia sinensis var. assamica which contain catechin in quite high amount compared with other countries tea plant. Green tea is made by inactivating the oxidase / phenolase enzyme that presents in the fresh tea leaf buds from tea garden, by using hot steam to prevent the oxidation of the catechins. Drying process to reduce the moisture of tea, one of the method is by utilizing the dry air from dehumidification process. Liquid desiccant made from 50% concentration of CaCl 2 , the temperature is lowered to 10 °C and sprayed into the air stream which contains water vapor by using a 0.2 mm spraying nozzle so that mass transfer and latent heat occur in the dehumidifier. The result of air dehumidification process used for drying tea leaves. The air is able to dry the tea leaves from the weight of 58 grams to 47 grams. Then the liquid desiccant dehumidification process will be streamed into the humidifier, where the liquid desiccant regeneration process will have change into the initial concentration. The result of air humidification process has an average absolute humidity rise of 0.07 g/kg. The liquid desiccant regeneration process that happened continuously reaching the saturation point at 280 minutes. It can be concluded that the process of dehumidification-humidification is a fairly effective method for drying the tea leaves.

Experimental Study Performance R-22 AC Split Retrofitted With Propane

Refrigerant 22 or called R-22 is still the most widely used for air conditioners. However, since it has a relatively high global warming properties, the use of R-22 should be stopped. Refrigerant 290 briefed as R-290 (propane) is the type of refrigerant recommended by many experts for R-22 replacements because the global warming properties of R290 are much lower than R-22. Therefore, in this study the cooling capacity, flow rate mass, power consumed and COP will be evaluated. The air conditioner engine used in this research has 1 PK capacity which is redesigned by adding separator / ducting on various main components of AC. From the result of the study, there are several conclusions revealed: on the same compressor capacity, R-22 cooling capacity is still greater than R290. Meanwhile, the flow rate of R290 is lower than R-22. For power consumption from R-290, it is smaller than R-22. For the value of COP R-290, the value shows greater ie at R-290 on the variation of Incoming Temperature In Evaporator 20oC = 6.23, 23oC = 6.36, 25oC = 6.86, 29oC = 6.20. While at R-22, it shows 20oC = 5.36, 23oC = 6.02, 25oC = 5.76, 29oC = 6.335

The development of the super-biodiesel production continuously from Sunan pecan oil through the process of reactive distillation

In general, a vegetable oil-based biodiesel production commercially operates a batch process with high investments and operational costs. Thus, it is necessary to develop super-biodiesel production from sunan pecan oil continuously through the process of reactive distillation. There are four advantages of the reactive distillation process for the biodiesel production, as follows: (i) it incorporates the process of transesterification reaction, and product separation of residual reactants become one stage of the process, so it saves the investment and operation costs, (ii) it reduces the need for raw materials because the methanol needed corresponds to the stoichiometry, so it also reduces the operation costs, (iii) the holdup time in the column is relatively short (5±0,5 minutes) compared to the batch process (1-2 hours), so it will reduce the operational production costs, and (iv) it is able to shift the reaction equilibrium, because the products and reactants that do not react are instantly separated (b...

The simulation of temperature distribution and relative humidity with liquid concentration of 50% using computational fluid dynamics

The study of humidity distribution simulation inside a room has been widely conducted by using computational fluid dynamics (CFD). Here, the simulation was done by employing inputs in the experiment of air humidity reduction in a sample house. Liquid dessicant CaCl2was used in this study to absorb humidity in the air, so that the enormity of humidity reduction occured during the experiment could be obtained.The experiment was conducted in the morning at 8 with liquid desiccant concentration of 50%, nozzle dimension of 0.2 mms attached in dehumidifier, and the debit of air which entered the sample house was 2.35 m3/min. Both in inlet and outlet sides of the room, a DHT 11 censor was installed and used to note changes in humidity and temperature during the experiment. In normal condition without turning on the dehumidifier, the censor noted that the average temperature inside the room was 28°C and RH of 65%.The experiment result showed that the relative humidity inside a sample house was decreasing up to 52...

Design of LLC resonant converter for street lamp based on photovoltaic power source

This topic presents a design procedure for the LLC resonant half-bridge converter configuration in the effort to be propossed to supply the LED street lamp. The main power is from Photovoltaic (PV). The paper is started a brief review about LLC converter and description of the relationship between input and output as a voltage ratio or voltage gain function. Next section is about to make simulation by PSIM software and hardware for circuit and compare the result.