RANCANG BANGUN THERMOBATH UNTUK KALIBRASI SUHU DENGAN TERMOKOPEL TIPE-K MENGGUNAKAN REFRIGERAN HFC-134

Thermobath adalah alat laboratorium yang berisikan air ataupun cairan lainnya sebagai beban pendingin yang dapat mempertahankan temperatur tersebut agar tetap konstan dalam waktu tertentu. Dalam perancangan thermobath penulis menggunakan kompresor 1/6 PK, pipa tembaga ¼ inch, katup ekspansi berupa ball valve, refrigeran HFC-134, dan fluida berupa air dengan volume 2 Liter. Perancangan didasarkan akibat mesin pemanas atau pendingin pada perindustrian dan perusahaan masih banyak memakai refrigeran yang memiliki potensi kerusakan lapisan ozon, penggunaan gas refrigeran semakin banyak untuk menjalankan suatu kerja pada sistem kompresi uap. Alat kalibrasi thermobath menghasilkan panas yang sesuai dengan yang terbaca pada alat ukur dengan bantuan termokopel yang sudah terkalibrasi. Penggunaan termokopel tipe-K ini dirancang menggunakan modul Arduino Max 6675 sebagai safety control agar thermobath tidak melebihi temperatur yang sudah diatur. Uji coba thermobath dilakukan hingga temperatur fluida mencapai 12°C dan 5°C, dengan nilai rata-rata pressure gauge sebelum dan sudah katup ekspansi berturut-turut 2,8 MPa dan 0,4 MPa serta 3,1 MPa dan 0,35 MPa. Laju pendinginan pada temperatur 12°C membutuhkan waktu 35 menit sementara laju pendinginan temperatur 5°C didapatkan dalam waktu 60 menit, laju pendinginan temperatur 5°C lebih lama sekitar 5 menit dan memiliki selisih paling besar 14,32% untuk mencapai suhu 12°C. Nilai COPaktual tertinggi ada pada pengujian temperatur 12°C dengan nilai 1,9 dan penyerapan kalor evaporator sebesar 78,403 kJ, dibandingkan uji temperatur 5°C dengan nilai 1,5 dan kalor serap evaporator 68,570 kJ

The Effect of Heat Flux on the Frequency of Bubble Appearance in a Boiling Pool

This research was conducted to determine the effect of heat flux on the frequency of bubbles appearing in boiling ponds. All fluid movement in pool boiling is caused by natural convection currents. The boiling pool consists of four areas of the pool boiling regime. The division of the four areas is based on the value of the heat flux and the difference between the surface temperature of the heater and the fluid. Using a two-phase heat transfer unit (H654 P.A. Hilton machine), The results showed that the power used greatly influences the boiling process, and besides that, the volume of water used also affects the duration of the boiling process. Based on tests using various power levels of 75 W, 110 W, 168 W, 237.5 W, and 290 W. The occurrence of bubbles will be faster and more numerous when using a lower volume of water and greater power. The heat transfer will be greater if a bubble appears, where latent heat plays a very important role. With mathematical analysis, an increase of 1 bubble per minute occurs for every increase in heat flux of 1.3 W/m2

Heat Transfer Coefficient Characteristic Study of Natural Refrigerant with Substitute for R-134a

The wide-spread use of halocarbon refrigerants are making negative impact on Earth. Natural Refrigerant, such as hydrocarbon, is one alternative of several option to use. Mixing hydrocarbon are develop to improve the heat transfer characteristic. For example is, Musicool-134 (MC-134) is a mixture with two major substance of propane and iso-butane. The experimental apparatus is using a microchannel with a diameter of 0.5 mm and length of 0.5 m. The evaporative process was conducted in the experiment. The result of the experiment is that if the high coefficient value then the heat flux value is also high

Study Characteristic Thermal Electric Generator (TEG) Type SP1848 27145 SA

The TEG component, which operates on the Seebeck principle like a thermocouple, is widely used in the market, with TEG SP1848 27145 SA being one of the most common types. However, experiments must be conducted to determine its Seebeck coefficient, voltage, and power output when used with different heat and cold sources. This research aims to observe how the Seebeck coefficient, voltage, and power output of TEG SP1848 27145 SA change with variations in system temperature. To experiment, TEG SP1848 27145 SA is tested with a heater, and water flow rates are varied for cooling. Furthermore, the correlation between output voltage and ΔT has been determined through statistical analysis. The experiment results showed that the voltage output ranged from 0.54–1.03 V at a heater temperature of 86°C and an ΔT system value of 70.5-75°C. The Seebeck value was between 1,551.7-2,998.5 µV, and the power output was 43.5-67.7 mW. Additionally, the statistical analysis found a significant correlation between the temperature variable and output voltage variable, with an adjusted r square value of 89.2% for zero water flow rate and increasing to 95.8% for maximum water flow rate

Effect of Liquid Reynolds Number on Pressure Drop of Evaporative R-290 in 500µm Circular Tube

Due to certain advantages, natural refrigerants have recently become more popular. Environmental issues motivate this study, focused on the characteristics of propane (R-290) as a replacement for conventional refrigerants. The aim of the present research is to characterize the pressure drop of evaporative R-290 in a microchannel of 500µm diameter and 0.5 m length. The variables of the experimental conditions are mass flux between 155 and 1071 kg/m2s and vapor quality between 0 and unity. The results show a laminar flow for liquid R-290 and a turbulence flow for vapor. Some existing correlations of two-phase flow viscosity were used to predict the pressure drop. For homogeneous model, Dukler et al.’s (1964) prediction viscosity correlation best predicted the present experimental pressure drop

Automatic Temperature Measurement And Monitoring System For Milling Process Of AA6041 Aluminum Aloy Using MLX90614 Infrared Thermometer Sensor With Arduino

Manufacturing process of metal part requires real-time temperature monitoring capability to ensure high surface integrity is upheld throughout the machining process. A smart temperature measurement and monitoring system for manufacturing process of metal parts is necessary to meet quality and productivity requirements. A smart temperature measurement can be applied in machining processes of conventional, non-conventional and computer numerical control (CNC) machines. Currently, an infrared fusion based thermometer Fluke Ti400 was employed for temperature measurement in a machining process. However, measured temperature in the form of data list with adjustable time range setting is not automatically linked to the computer for continuous monitoring and data analysis purposes. For this reason, a smart temperature measurement system was developed for a CNC milling operation on aluminum alloy (AA6041) using a MLX90614 infrared thermometer sensor operated by Arduino. The system enables data linkages with the computer because MLX90614 is compatible and linked to Microsoft Exel via the Arduino. This paper presents a workstudy on the performance of this Arduino based temperature measurement system for dry milling process application. Here, the Arduino based temperature measurement system captured the workpiece temperature during machining of Aluminum Alloy (AA6041) and data were compared with the Fluke Ti400 infrared thermometer. Measurement results from both devices showed similar accuracy level with a deviation of ± 2 oC. Hence, a smart temperature measurement system was succeesfully developed expanding the scopes of current system setup

Optimization of the Friction Factor and Frictional Pressure Drop of R22 and R290

Today, the air-conditioning and refrigeration industry is still searching for environmentally friendly refrigerants that could replace hazardous, ozone-depleting coolants – refrigerants that behave similarly, if not better, than the present ones. The present study examines optimization of the frictional pressure drop of R22 and R290 using genetic algorithm. Outcomes are compared against the measured pressure drop obtained from a horizontal 7.6 mm channel with a length of 1.07 meters. Three equations have been used for calculating the Darcy friction factor and two-phase flow pressure drop for both laminar and turbulent flow regimes in smooth and rough tubes. The effects of the different correlations for the friction factor and pressure drop utilized are demonstrated. The results illustrate that the differences between values of the Darcy friction factor are very small for the two refrigerants examined, with the frictional pressure of R-290 higher than R-22. Use of a smaller channel induced a much higher frictional pressure drop, as well

Rancang Bangun Sistem Pengukuran Alat Thermobath sebagai Alat Kalibrasi Temperatur dengan Sistem Arduino Uno

A thermobath cooler is a device that contains water or other liquid as a coolant that can maintain a constant temperature. The control system designed in this study uses a K-type thermocouple temperature sensor and pressure transmitter microcontroller-based, namely Arduino Uno to be able to produce temperature and pressure measurement data on the thermobath through the software PLX-DAQ. This system thermobath requires a K-type thermocouple component and apressure transmitter JYB-KO-H. Before being placed in the system thermobath, the K-type thermocouple and pressure transmitter are required to calibrate. Based on the results of the temperature and pressure calibration equation, the coefficient of determination (R2) on the K-type thermocouple ranges from 0.9986 to 0.9998 and the coefficient of determination (R2) at the pressure transmitter is 0.9994. With the calibration results, the design of measuring thetool thermobath as a temperature calibration tool with the Arduino system can be applied to thecooling system thermobath