Pengaruh Kecepatan Fluida Pendingin (Udara) Terhadap Unjuk Kerja Dan Karakteristik Perpindahan Panas Pada Radiator Sepeda Motor Yamaha Nmax 155CC

Penelitian ini menggunakan metode ɛ-NTU untuk menganalisis data. Radiator yang digunakan adalah radiator sepeda motor Yamaha Nmax 155cc dengan jenis aliran vertical, flat tube dan louvered fins, kipas/fan sebagai sumber angin simulasi, dengan campuran 50% air + 50% coolant radiator. Laju aliran air konstan 4 lpm dan temperatur fluida panas konstan 80. Variasi kecepatan aliran udara yang digunakan pada pengujian kali ini adalah 4-8 m/s dan diatur menggunakan Dimmer sebagai alat bantu. Dari pengujian yang telah dilakukan didapat laju massa aliran udara yang paling besar terjadi pada kecepatan kipas 8 m/s. Laju perpindahan panas yang paling besar terjadi dikecepatan kipas 8 m/s sebesar 0,0735 kW dan panas menyeluruh terbesar juga terjadi dikecepatan kipas 8 m/s yaitu sebesar 9,50 W/m2°C. Efisiensi radiator maksimum terjadi pada kecepatan kipas 5 m/s dengan nilai sebesar 7,59. Kata kunci: Efektifitas, Metode ε-NTU, Radiator Nmax 155cc. This study uses the ε-NTU method to analyze the data. The radiator used is a 155cc Yamaha Nmax motorcycle radiator with vertical flow type, flat tube and louvered fins, fan/fan as a simulation source, with a mixture of 50% water + 50% coolant radiator. The water flow rate is constant 4 lpm and the hot fluid temperature is constant 80℃. The variation of air flow velocity used in this test is 4-8 m/s and is adjusted using a dimmer as a tool. From the tests that have been carried out, the largest air flow rate occurs at a fan speed of 8 m/s. The highest heat transfer rate occurs at a fan speed of 8 m/s at 0.0735 kW and the largest overall heat also occurs at a fan speed of 8 m/s at 9.50 W/m2°C. The maximum radiator efficiency occurs at a fan speed of 5 m/s with a value of 7.59 Keywords: Effectivenes, ɛ-NTU Method, Nmax 155cc Radiator

Improving the efficiency of carousel wind turbine using aerodynamic shield

The problem of increasing the efficiency of using the oncoming air flow for a wind wheel with a vertical axis of rotation, which is a mechanical drive of the wind heat generator, is considered. It is proposed to increase the efficiency of the device by installing an aerodynamic shield for the air flow oncoming the wind wheel. Such a shield is a cylindrical body in which a heat generator is placed. The shield creates an effect of confuser, leading to an increase in the speed and, consequently, in the kinetic energy of the air flow acting on the rotor blades. It is shown experimentally that the presence of an aerodynamic shield under the conditions of the experiments carried out at an incoming air flow velocity of ~ 1 m/s leads to a practical doubling of the wind wheel torque.

Study on the process of droplet formation when liquid flows out of a capillary

This article presents the theoretical background for the justification of the parameters of the rotating sprayer. Theoretical studies show that an increase in the rotation frequency of the disk at a constant air flow velocity leads to a minimum median mass diameter of the droplets. Therefore, when justifying the diameter of the sprayed droplets, it is necessary to consider the combination of the disk rotation speed and the axial velocity of the air flow. To obtain high-quality air-droplet flow, the initial speed of the main droplets discharged from the periphery of the spray disc should be less than the air velocity and rotational frequency Pavlovskyi spray is recommended to be applied with in ω=60… 200 c1.

Thermal Resistance Model of a Flat Plate Solar Air Collector for Energy Efficiency Prediction

The temperature of a PV panel rises during operation which affects its power output. A PV panel is similar to a flat plate solar collector. This paper presents a simple theoretical heat transfer resistance model and a solution procedure to predict the absorber plate surface temperature of the solar collector. The model consisted of a rectangular cross-section steel duct placed inclined at an angle to the horizontal and exposed to solar radiation. The heat absorbed on the top surface of the plate is transmitted by conduction through the plate and heats the air in the duct. This creates a natural buoyancy effect which induces a natural convection air flow rate. A simple one-dimensional theoretical model of the solar collector with the thermal resistances of the various components is proposed. Simulated results of plate temperature and induced air flow velocity are presented.

Performance test of greenhouse effect (GHE) vent dryer with the addition of paraffin as a heat storage medium

Green House Effect (GHE) vent dryer is a kind of dryer design by utilizing solar energy as a drying energy source. Adding paraffin as a heat storage medium is one solution so that the GHE vent dryer can operate when the solar energy has dimmed. The purpose of this study was to test the performance of heat storage media using paraffin as a heat storage medium. 9 kg of paraffin was prepared, put into 9 copper pipes and placed in the absorber chamber. The data measured were the temperature in the drying room (T1=room 1, T2=room 2 and T3=room 3), the temperature of the absorber room, the temperature of the outlet, ambient temperature, air velocity and solar radiation. The results showed that the average ambient temperature ranged from 30°C to 40°C. Meanwhile, the average temperature in the GHE vent dryer ranges from 69°C to 71°C. The drying air flow velocity in the environment reaches 1.3 m/s and on the ventilator 1.1 m/s. During the study, data on solar radiation was also obtained on average reaching 6.6 W.h/m2. The final conclusion of this study shows that the use of paraffin as a heat storage medium in the GHE vent dryer is able to maintain the temperature in the drying chamber for 4 to 5 hours when solar radiation is not present.

Calibration platform controller of the laser Doppler anemometer

Primary standards for the unit of air flow velocity often use a Laser Doppler Anemometer (LDA) as the primary measurement standard. A rotating disc with a fixed diameter is used to calibrate LDA. The paper proposes calibration platform based on the precision mechanics of HDD disk. A disk rotation controller has been developed for the platform. Deviations of the disk rotation speed do not exceed 0.01% RMS in the range of angular speeds of 600-4800 rpm.

Effects of Plate Edge Thickness On Droplet Generation Caused by Water Film Breakup At the Plate Edge

Droplets generated at trailing edges of low-pressure steam turbines strike the leading edge of moving blades, resulting in severe damage by erosion. In this study, water film flows on a plate set in a parallel airflow and breakup patterns are observed and measured to investigate the breakup behavior of the water film at the plate edge and the effect of the plate edge thickness. Profiles of frequency distribution of the droplet diameters exhibit on approximately linear in a semilog graph. The gradient of those distributions becomes steeper when the air flow velocity increases. Coarse droplets are generated from the deformation of ligaments, as shown in the end stage of a sheet-type breakup, and will result in a secondary breakup. Meanwhile fine droplets whose diameters are similar to the critical diameter remain in the high airflow velocity region; they are assumed to contribute significantly to erosion damage. The plate edge thickness does not affect the frequency distributions of the droplet diameter and Sauter mean diameter. However, it affects the intermittency of discharge water. The discharged water period becomes longer when the plate edge thickness increases. This discharged water frequency is smaller than the wave frequency of the water film flow on the plate when the airflow velocity is high. Based on an experiment involving the highest airflow velocity, the discharged water frequency is similar to that generated by a general turbine rotation speed.

Theoretical and experimental study of the effect of mini channel finned heatsink on TEG performance in air-cooled environment

Air-cooled finned heatsink (FHS) are more compact then water-cooled heatsink due to no water channel, which is beneficial to simplify the structure of the cooling side of the thermoelectric generator system. Therefore, a mini channel finned heatsink (MCFHS) was designed in this study based on Venturi effect. In this study, the mathematical model of TEG with MCFHS and FHS were developed and verified. The effects of the heating temperature and air flow velocity around the heatsinks on the TEG performance were analyzed and demonstrated. The TEG performance was investigated in terms of the temperatures of the two sides of the TEG, the TEG voltage, and the TEG efficiency. The results revealed that the smaller thermal resistance of heatsink is favorable for greater output of TEG. And the use of the MCFHS can effectively improve the performance of the TEG under different conditions. The maximum TEG efficiency with MCFHS could be 155% higher than the TEG with FHS.

PEMODELAN MATEMATIKA ALIRAN UDARA PADA PARU-PARU AKIBAT PENYAKIT CORONAVIRUS DISEASE 2019 (COVID-19)

The bronchial airways are an important part of the respiratory system, it is not uncommon for the bronchi to experience disturbances, one of the disorders due to coronavirus diseases (Covid-19). Coronavirus diseases (Covid-19) are what cause narrowing of the bronchial tubes so that they will interfere with the speed of air flow. This airflow speed will be modeled with mathematical language. The mathematical model of air flow velocity in this study is formed based on equations of momentum equations which are then solved by the finite element method. Speed ​​analysis Air flow was simulated using MATLAB and FLUENT software. The problems studied are the effect of the narrowing diameter, initial velocity, and viscosity on the air flow velocity. Based on the research results show that the smaller the narrowing diameter and the viscosity of the incoming air, the greater the airflow velocity, while for the greater the initial velocity, the greater the resulting airflow velocity. Keywords: Coronavirus Diseases 2019 (Covid-19), bronchial, lungs, airways, finite element method.

Investigation of Stability Limits of a Premixed Counter Flame

In combustion operations, flame fronts are often spread in an irregular. Therefore, the temperature and flame speed varies along the flame's front and depend on the asymmetry of the composition of the mixture and the conditions of the local flow before the flame, especially this behavior is evident in double counter flames. This paper describes an analytical study of stability limits of premixed counter flame. The investigation is based on experiments carried out to identify the effect of varying the distance between upper and lower burner edges on the stability limits at different equivalence ratio values; liquid petroleum gas (LPG) was used as fuel in experiments. The blow-off limit, disc flame limit, and double flame limit were investigated. Under the change of fuel gas-air flow velocity, in this type of flames, the conical flame is transformed into mushroom-shaped tented flame attached to the widened convex apex in the medial distance between the upper and lower burner edges. The experimental data and numerical analysis obtained show that high-stability for double flame, fuel-rich premixed flame operate over narrow range of equivalence ratio φ from 0.43 to 1.41. The ANSYS 17.0 FLUENT Premixed Flamelet Module with pre-processing was used. The results appear that increasing distance between burner edges decreases the flame stability efficiency.