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Transitioning to renewable energy requires a micro approach at the household level as decision-makers. This paper investigates the characteristics of photovoltaic (PV) system adopters and non-adopters of photovoltaic (PV) systems in Indonesian households to recognize household heterogeneity and explores empirical facts regarding the critical factors influencing PV system adoption. A survey of 450 households was conducted in 2020. The results showed that the adopter and non-adopter groups differed significantly in their activeness in seeking information about PV and the recommendations received for using PV. However, the effect of suggestions and sources of information was the same between the two groups. Both groups have the same perception of the benefits derived from PV systems and the high investment costs. However, they are significantly different in perceptions of the complexity of using PV systems. The research shows that the adopter group is an early adopter, while the non-adopter group has late adopter characteristics. Regarding environmental value, the two groups did not show a significant difference concerning the problem of awareness and responsibility for using renewable energy. However, they differed in willingness to pay more for using renewable energy. Electricity bill reduction, energy independence, and environmental friendliness are the three primary motivators for adopting groups to install PV systems. Meanwhile, in the non-adopter group, high installation costs, access to installation services, and lack of information were encountered as the main obstacles to adoption. The non-adopter group will be willing to use the PV system if given a 55% subsidy of the investment cost and when the payback period is not more than 8 years. [ABSTRACT FROM AUTHOR]

Transitioning to renewable energy requires a micro approach at the household level as decision-makers. This paper investigates the characteristics of photovoltaic (PV) system adopters and non-adopters of photovoltaic (PV) systems in Indonesian households to recognize household heterogeneity and explores empirical facts regarding the critical factors influencing PV system adoption. A survey of 450 households was conducted in 2020. The results showed that the adopter and non-adopter groups differed significantly in their activeness in seeking information about PV and the recommendations received for using PV. However, the effect of suggestions and sources of information was the same between the two groups. Both groups have the same perception of the benefits derived from PV systems and the high investment costs. However, they are significantly different in perceptions of the complexity of using PV systems. The research shows that the adopter group is an early adopter, while the non-adopter group has late adopter characteristics. Regarding environmental value, the two groups did not show a significant difference concerning the problem of awareness and responsibility for using renewable energy. However, they differed in willingness to pay more for using renewable energy. Electricity bill reduction, energy independence, and environmental friendliness are the three primary motivators for adopting groups to install PV systems. Meanwhile, in the non-adopter group, high installation costs, access to installation services, and lack of information were encountered as the main obstacles to adoption. The non-adopter group will be willing to use the PV system if given a 55% subsidy of the investment cost and when the payback period is not more than 8 years. [ABSTRACT FROM AUTHOR]

This study developed a conceptual framework based on the Unified Theory of Acceptance model and Use of Technology2 (UTAUT2) to understand the behavioral factors underlying intention to adopt solar photovoltaic (PV). The present study extends the framework to include personal norms to explain the intention to adopt solar PV. The present study investigates the behavioral factors underlying the intention to adopts Unified Theory of Acceptance and Use of Technology solar PV by Indonesian households. An empirical survey involving 413 Indonesian households from all 34 provinces in Indonesia was carried out in 2020. Based on binary logistic regression, out of the 13 factors being investigated, it was found that personal norms, age, performance expectancy, price value, and facilitating condition (i.e., accessible infrastructure and service) have statistically significant influences on the intention to adopt the solar PV. The model has a classification accuracy of 74% and can explain the 27% of the intention variance. The findings imply that in addition to financial benefits and affordability, facilitating conditions in terms of the availability of supply, installation, and maintenance services play a motivating role in adopting solar PV. Further, personal norms are also a significant factor toward the intention to adopt solar PV. Potential interventions to drive up the intention to adopt solar PV are also discussed. [ABSTRACT FROM AUTHOR]

Indonesia has 40% of world's geothermal potential. The utilization of geothermal potential is not only used for electrical power plant, but also direct usage such as tourism. One of geothermal tourism in Indonesia is a hot spring in Leilem Village, North Sulawesi. Leilem's geothermal hot spring has high level of acidity that potentially cause skin's damage. To overcome this problem, this research designs a sustainable technology to increase pH level by reacting the water with limestone (CaCO3). The water was classified as sulfate water because it contains high concentration of acid sulfate (H2SO4) and has the pH level below than 3. The reaction is assumed to obey Arrhenius' Law. Runge Kutta method is applied to calculate the reaction constants which will be verified using experimental data. The equipment can be designed based on these constants. As a result, the equipment can increase the pH level up to 4 which is the most suitable pH level for bath. [ABSTRACT FROM AUTHOR]

Biodiesel is an alternative fuel derived from plant oil, animal fat or used oil through esterification with alcohol where it can be used without modifying the engine of a diesel machine. Used cooking oil is categorized as a waste that pollutes the environment, which can be the cause of some diseases such as cancer, coronary heart disease, stroke, and also hypertention. Calcium oxide (CaO) is an alkali metal oxide that can be used as a heterogeneous catalyst in biodiesel synthesis, its raw materials can be sourced from waste material such as chicken bones. The conversion of calcium to CaO is conducted through thermal decomposition of calcium carbonate (CaCO3) from chicken bones heated at a high temperature. This study utilizes used cooking oil as the raw material and CaO as the catalyst. The purpose of this study was to determine the effect of the amount of catalyst in the biodiesel synthesis from used cooking oil and also the effect of temperature variation on chicken bone heating as the material of the catalyst. This study was carried out by transesterification and calcination procedures with temperature variations of 700, 750, 800, 850 and 900°C, as well as the variations in the amount of CaO as the catalyst of 2, 3, 4, 5, and 6 % wt. This study shows that the most favorable calcination temperature for the chicken bones is at 750°C and the percentage of CaO as the catalyst is 2%. [ABSTRACT FROM AUTHOR]

The lattice Boltzmann method development gave the insight of the new alternative way of simulation. In this study, we modify the LBM scheme for Rayleigh-Taylor instability multiphase case. By comparing with the other numerical method of RTI case, the current LBM model was successfully simulated the RTI phenomenon precisely. The quantitative study of bubble and spike position is investigated and shows a similar result with the previous study. Moreover, the qualitative result of late-time RTI development simulation is also presented as well. [ABSTRACT FROM AUTHOR]

Airlift pump has a several flow pattern in lifting mixtures liquids and solid through a vertical pipe. The flow pattern in airlift pump have been investigated in previous studies, the study focus on two-phase flow and performance of air lift pump. For this reason, the purpose of experiment was to known the flow pattern of gas-solid-liquid three-phase flow in airlift pump during the solid particles lifting in the upriser. In the present experimental study, we have modified the conventional airlift pump system by used swirl injector in the system. Here, experimental study on the flow pattern of gas- solid-liquid three-phase flow in upriser airlift pump to lift the solid particles with the vertical pipe as the transporting medium was conducted. The upriser pipe was an acrylic pipe with an inner diameter at 56 mm, and the total height of 340 cm. The type of gas injector in the system was swirl with 2 injectors in suction head of air lift pump. The solid particle of the present experiment was sand with particle diameters 0.774 mm and 1.43 mm, and the supplied air flow rate ranged from (60-80 LPM). The solid lifting particles were capture by using a high speed camera of the frame speed of 3000 fps. As a result, it was obtained that (1) the optimum of solid lifting particle was found in the slug flow pattern, (2) the particle diameters and volumetric flow rate of the lifted particles affect the ability of the air lift pump. [ABSTRACT FROM AUTHOR]

The combined cycle power plant (CCPP) has higher thermal efficiency compared to steam power plant (SPP) and gas turbine power plant (GTPP). It combines gas turbine/ brayton cycle and steam/ rankine cycle. A study has been carried out to determine the effect of gas composition, air intake cooling and steam injection on the performance of the CCPP using Aspen Hysys V9 process simulator. The validity of simulation has been confirmed that shown by minor error of less than 10% in comparison with manufacturer data. The results showed that changes in gas composition caused a decrease in power of 0.23 - 3.92 MW. The inlet air temperature and steam injection configurations were found to have a positive effect in increasing the efficiency of 1.97% - 8.03% and 4.24% - 4.59%, respectively. [ABSTRACT FROM AUTHOR]

Along with the development of the population in a region in a coastal area will be directly proportional to the need for clean water. However, the thing that usually happens is that there is an imbalance between water availability and water needs, in order to achieve this aspect in the future, further research is needed to achieve the water demand target in coastal areas. However, sea water still has a high TDS (Total Dissolved Solids) content and salinity, so it is not suitable for use. To desalinate sea water must increase the sea water temperature until conditions are above the saturation temperature. In this study, we will discuss how the influence of condenser pressure and salt concentration on aquades production and specific energy consumption to prove how capable and efficient the throttling process is in producing aquades water, which is expected to help provide water to meet water needs. [ABSTRACT FROM AUTHOR]

Ethanol was widely used as gasoline additive because it can improve the combustion performance. In the other hand, the addition of ethanol in gasoline could increase the Reid Vapor Pressure (RVP). High value of RVP could lead to high emission evaporation. The objective of this study were to obtain experimental vapor liquid equilibria (VLE) data of gasoline and ethanol system using modified ebulliometer. The types of Gasoline used in this study are Petrosol CA, Petrosol CB and Petrosol CC. The addition of ethanol in Petrosol CA, Petrosol CB and Petrosol CC increased vapor pressure of the gasoline mixture up to 18.6 kPa, 12.9 kPa, and 8.2 kPa, respectively. The VLE data was then correlated with NRTL equation as temperature function. The best correlation result was obtained by modified NRTL activity coefficient with average absolute deviation (AAD) for ethanol (1) – Petrosol CA (2), ethanol (1) – Petrosol CB (2), and ethanol (1) – Petrosol CC (2), are 3.7 %, 3.7 % and 1.7 %. [ABSTRACT FROM AUTHOR]

In this study a new multi-generation system, which generates power (electricity), thermal energy (heat and cooling) and ash for agriculture has been developed and analysed. The system consists of a Biomass Integrated Gasification Combined Cycle (BIGCC) and Absorption Chiller (AC) systems. Energy and exergy analysis of this multi-generation system has been conducted, and exergy destruction in system components has been calculated. The results of this study show that 3.4 MW of electricity, approximately 4.6 MW of heat, 88 kW of cooling and 90 kg/h of ash for fertilisation can be generated. The exergy analysis shows that highest exergy destruction occurs in the gasifier and combustor of BIGCC system and in the generator, condenser and absorber of AC system. [ABSTRACT FROM AUTHOR]

Water is a very important substance in human life. The type of water that humans need is clean water. However, 97.7% of the water available on earth contains salt, so it is not suitable for use. Humans have made many efforts to convert seawater into freshwater by various methods, one of which is the desalination method to increase water resources and improve water quality. In this study, there are two methods used; experimental and simulation method. The experimental method uses experimental devices to prove that this system can be applied to the steam power plant and to see the effect of water mass flow and water salinity on specific aquades production, the experimental method only includes the throttling process and not integrated to steam power plant cycle. The simulation method uses theoretical calculations as a system that has been integrated into the power plant to obtain the value of specific energy consumption. Briefly, hot water waste from a power plant condenser can be used as a water source by using the desalination method. Thermal method and throttling process, hot water waste from the condenser can reach the saturation pressure and temperature. The throttling process is a method to limit the water flow to reduce pressure. The simulation method it can be proven that the pinch point and percentage of water waste are affecting Specific Energy Consumption (SEC). From the simulation results, the best SEC data obtained at 7.5°C pinch points and 99% wastewater percent with SEC value of - 1691.65 kJ/kg. An experimental method was also conducted to prove that this throttling process can be implemented. This experimental method produces aquades that directly proportional to mass flow and inversely proportional to the salt concentration. The best aquades production from the experimental method is 32 ml/min, which is obtained at temperature 130°C and mass flow 600 ml/min. [ABSTRACT FROM AUTHOR]

The use of commonly used vapor compression cycle cold storage in fishing vessel is facing limitations to be widely applied in Indonesian fishermen since it consumes more energy and requires large space. Thermoelectric refrigerator is believed to be a promising option due to its simple design and low energy requirement. However, the Coefficient of Performance (CoP) of the system in current development is relatively low. Although many researches have been conducted to increase the CoP of the system But there is still lack of studies focused on effects of the important variables to cold storage performance. The present study aimed to investigate the effect of input voltage on thermoelectric cold storage chamber temperature in the form of transient behaviors. As a result, it was found that the increase of input voltage significantly affected the cooling performance, although in 6 V input voltage, the result is only a bit lower than 12 V with much lower energy use. In addition, the time needed to get steady state in 12 V was the fastest compared to the other input voltages. Those results can be used as design consideration of a portable thermoelectric cold storage. [ABSTRACT FROM AUTHOR]

The effect of ambient wind on the performance of an air conditioning unit has been experimentally tested based on ISO Standard 5151 (2017). The test was conducted under 35°C dry bulb (db) and 24°C wet bulb (wb) ambient temperature, while the indoor is at 27°C db and 19°C wb. A split air conditioning unit was tested under normal condition and windy conditions. Under normal conditions, the outdoor unit was tested as if no wind in the ambient air. Under windy condition, a constant 6.5 m/s wind was directed 30°, 45°, 60°, and 90° from the outlet side of condenser. The results of the experiment showed the increase of refrigerant discharge temperature and condensing temperature when the condenser was subjected to wind. It is also shown that the supply air temperature increases with the presence of wind. The decrease of cooling capacity by 7.9% is found for windy condition while the power consumption increase by 10.2%. This gives the drop of energy efficiency ratio by 16.5%. Overall, the frontal wind (90° direction) has the most devastating effect on the performance of the air conditioning unit. [ABSTRACT FROM AUTHOR]

Microbubble generator is a device that produces micro-sized bubbles that are useful to increase the dissolved oxygen in the water. This present work investigates the effect of the swirl flow created by the cyclone of a 12 mm orifice type microbubble generator using a 300 mm stainless steel wire mesh porous tube. To review the performance of the microbubble generator, three parameters were considered. Those are the hydraulic power (Lw), pressure drop, and bubble diameter distribution. The hydraulic power and pressure drop values were acquired by using the pressure sensor of Validyne P55D, while the bubble diameter distribution was obtained using a high-speed camera. The results indicate that the bubble diameters appear with the highest probability in the diameter range of 300 - 450 µm. The increase of water and airflow rates cause the rise of the hydraulic power and pressure drop. [ABSTRACT FROM AUTHOR]

Due to a huge amount of energy consumed by an air conditioning (A/C) system in buildings, several methods and technologies have been developed to enable this system works in the more efficient way. One of the methods is to regulate the room temperature without ignoring human thermal comfort in the air conditioned space. In the A/C system, the higher the room temperature setting, the lower the energy consumption. To investigate the effect on the energy consumption of A/C system due to difference room temperature setting, an experimental study on the A/C system with cooling capacity of 3.7 kW using R32 as working fluid was conducted. In this study, the room temperature was set from 20 to 24°C, with temperature increment of 1°C. The measurements were carried out for 180 minutes for each room temperature setting. The results show that the energy savings due to increment of 1°C from 20 to 21°C, 21 to 22°C, 22 to 23°C and 23 to 24°C are varied. The biggest and lowest energy consumption reductions occur at 21 to 22°C and 23 to 24°C, which are 13.5% and 10.7%, respectively. As a result, the increment in room temperature setting of 1°C from 21 to 22°C generates the most significant energy saving as compared to other setting temperatures. [ABSTRACT FROM AUTHOR]

Simulations for co-axial types are carried out in two types, namely the kind where the inner tube inserted into the resonator area and the second type of inner tube inserted through the thermoacoustic core. In the first type of co-axial simulation the acoustic power produced was much smaller compared to the kind of standing wave, while the second type of co-axial simulation obtained higher acoustic power compared to the type of standing wave. Performance simulation on the co-axial thermoacoustic engine (CoATE) with 25 mm inner tube diameter showed that the acoustic energy generated at 30.65 watts, 30.23 watts, 29.62 watts, 28.83 watts, and 27.85 watts for 580 mm, 530 mm and 480 mm, 430 mm, and 380 mm inner pipe, respectively. [ABSTRACT FROM AUTHOR]

Problems associated with the development of the first and second generations of biofuel, especially regarding its raw materials and complex processes, have led to the evolution of the third generation one, a microalgae-based bio-oil through pyrolysis. This research explored the effect of temperature ranging between 300−700 °C and the presence of Silica−alumina (Si-Al) catalyst at the variation of 5–20 wt.% on the pyrolysis process of Spirulina platensis microalgae solid residue, in search of optimum condition for collecting maximum bio-oil yield and its desired composition. The experiments without catalysts reached their optimum yield of 28 wt.% at 550 °C. While the involvement of 5 wt.% of Si- Al catalyst in the reactor resulted in a higher yield than that of without catalyst beyond 550 °C. Furthermore, a high amount of catalyst content at 20 wt.% seems to improve bio-oil yield collection up to 34.10 wt.%. Interestingly, referring to its C atoms number, SPR-based bio-oil by catalytic pyrolysis tended to produce such a considerable amount of gasoline leading to Pertamax, and the one without catalyst produced gasoline leading to Pertalite. [ABSTRACT FROM AUTHOR]

Most of geothermal power plants experience the deposition problems, mainly silica scaling that exhibits in the brine pipes and/ or the reinjection system. Many techniques have been introduced to overcome this problem, such as hot brine injection system, cold brine injection system and acidizing. Experiences showed that these techniques seemed not to be effective in handling the problems. This study proposes a technique of handling the scaling problem by separation process between liquid and solid using hydrocyclone separator where the solid phase is produced by adding a chemical into the brine. The reaction process between chemical and brine is not considered in this study. Before the manufacturing process, the numerical simulation on the separation process in the hydrocyclone separator is important to be carried out for the guidance in designing the appropriate separator geometry that meets the operating condition. The simulation was carried out using ANSYS Remote Solve Manager (RSM) and Discrete Phase Model (DPM). In this model, the fluid density was assumed to be constant and the inlet pressure was given for boundary condition. The mass flow rate of brines and the particles size were varied to evaluate the effects of these parameters on the cyclone efficiency. The simulation results showed that the values of particle size of 53 µm and the brine mass flow rate of 100 kg/s, respectively give the cyclone efficiency of 86 %. The cyclone efficiency increases as the fluid mass flow rate becomes larger. [ABSTRACT FROM AUTHOR]

Indonesia located in equator area has abundant biomass which is the most attractive source among other alternative resources. Biomass also represents a high potential for the sustainable production of both valuable chemicals and biofuels. Biomass in Indonesia offers abundance, easy availability, carbon neutrality, and eco-friendly features make a positive impact on this situation, decreases of oil reserves and increases prices of oil-based fuels. Thermo-chemical routes considered as a suitable technology for utilization of biomass like Hydrothermal Liquefaction (HTL) to produce Bio Crude Oil (BCO). Various solvents like water, alkali, polar, and organic acid were examined to observe the characteristic of process at 300°C. HTL was conducted in 1000 ml high pressure and temperature reactor. This work used frond oil palm which is abundantly available and untapped resources in palm plantations. The experiment confirmed that the pressure in reactor depend on the vapour pressure of the solvent. In addition, the vapor pressure is also determined by the boiling point. Water and alkali solvent gave the same operating pressure as indicated by the vapor pressure of water, 82 bar. Unfortunately, the biomass was polymerized at 300°C. To prevent the polymerization, a commercial cracking catalyst was added to break the polymer chain of the product. Regarding the product, water, as a solvent, produced bio-char 37%. Alkali solution has a role to breakdown part of lignin so that the char decreased to 30%. In addition, further degrade biomass could be work more effective by combining cracking catalyst like NiMo that showed by formation of CO, CO2 and CH4. Those gases formation showed decarboxylation, decarboxylation, and cracking process, respectively. Catalyst as expected, avoid the polymerization that can be seen at powdering of biochar. The catalyst worked more effective in acid condition as shown by more CH4 in syngas. Unfortunately, the liquid product was still dominated by water, more than 80% and the yield of BCO was considered very low. TGA analyzed showed the volatile compound that vaporized between 110-300°C was considered the component that might cause be converted into water. Therefore, the work would focus more at chemicals content produced by HTL like acetic acid, phenol, ester, and ether. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicles (UAV) are used in the military field for missions such as observation, surveillance and seeking object. UAV observation can be used to monitor humans, weather, forests, agriculture, and fisheries and so on. UAV can be operated for very broad missions with low development costs compared to manned aerial vehicles with a low risk of death. The design of an aircraft affects the performances of the aircraft itself. Aircraft flying characteristics are influenced by the value of coefficient of drag (CD) and coefficient of lift (CL). The value of CD affects how much aircraft friction with the air, while the value of CL affects how much lifting force the aircraft is produced so it can fly. The design output needs the most optimal CD and CL values to get the optimal aircraft performance. In this study, we simulated the effect of 4 digit NACA changes on the characteristics of the plane's CD and CL. This study uses variations modification of NACA digits with different variables. NACA airfoil 4 digit series (MPXX) designates camber lines, maximum camber position and thickness. Based on the results of this study, the optimal CD and CL values for the Airfoil NACA with the Aerosonde UAV model are designs that have a large ratio of lift and drag (CL / CD). The lower the CD value and the higher the CL value, the better the performance of the UAV. The design that has the largest CL / CD is the NACA 6412 Airfoil. [ABSTRACT FROM AUTHOR]

This paper gives an overview of several published current studies concerning heat transfer enhancement on the double pipe heat exchanger. Since double pipe heat exchanger has drawn much consideration due to simplicity and wide-range utility. The flow manipulation technique to enhance heat transfer in a double pipe heat exchanger has been frequently cited. Also, various research addressing working fluid on a double pipe heat exchanger has been discussed in detail. Another technique is known as surface modification that has an infrequent investigation comparing the other techniques. Correlation of Nusselt number and pressure drop coefficient shown in this overview. Future research opportunities are mentioned. [ABSTRACT FROM AUTHOR]

The 500kW Lahendong binary cycle geothermal power plant is the first low-medium enthalpy generation system commenced in Indonesia. The pilot plant was established through technology research collaboration among BPPT, GFZ and PT. Geothermal Energy. The proven ORC unit is built by a German industry, where heating and cooling systems are manufactured by national industries. Construction and installation of the pilot plant was completed in 2016. Since September 2017, the pilot plant has continued to operate. The main target of the Indonesian-German cooperation is to disseminate the binary cycle technology throughout Indonesia. This paper discusses operating experience of the plant 500kW during the past six-month period. As a result, to achieve the design conditions (500 kW gross and 424.2 kW net), further work needs to be done. [ABSTRACT FROM AUTHOR]

One of the tea processing that affects the quality of tea is the drying process. The tea drying process was simulated using CFD software to get temperature distribution of tea also determine the optimal value of velocity and temperature inlet. The tea drying simulation is carried out on cylindrical tea, which has a size of D = 3.5 mm and p = 14 mm by placing tea material on the computational domain of external flow. Tea Drying Simulation uses inlet velocity and inlet temperature variations. Variations in velocity used are 2.5 m/s, 3.5 m/s, and 4.5 m/s, while the temperature variations used are 87°C, 92°C, and 97°C. The flow model used is laminar flow. The results showed to achieve the condition of moisture content of tea particles to 5% (1.5 g) the fastest drying time occurs at velocity of 4.5 m/s with the temperature of 97°C is about 348 seconds, while the slowest drying time occurs at velocity 2.5 m/s with an inlet temperature of 87°C is around 652 seconds. [ABSTRACT FROM AUTHOR]

Grashof incubator has continuously changed for improvement from A-type to G-type as an effort to increase quality both in physical and thermal terms. The unchanging part is the use of an analog thermostat as an electrical cut-off based on the upper limit of temperature. The accuracy and uniformity of the analog thermostats are not reliable. This is the main cause of the performance of several grashof incubators that are not uniform with each other. Changes in the heating chamber design and the use of TD-W1209 digital thermostats that are applied to the H-type prototype grashof incubator are intended so that their performance is following SNI IEC 60601-2-19: 2014 (Indonesia National Standard) criteria. By using these standards, it can be seen the effect of the digital thermostat on heat performance, especially the accuracy of temperature and uniformity in the baby's cabin of G-type and H- type. From the results of changes in H- type, the average reading deviation in the device is only about -0.65°C (from +/- 1.5°C tolerance). Uniformity in-cabin temperature increased to 93,8% in H-type from previously only 88,1% on G-type. Modification of the heating chamber design and applying W1209 digital thermostats, placing the H-type in good accordance to the SNI IEC 60601-2-19: 2014 criteria. [ABSTRACT FROM AUTHOR]

Computational study of flow and heat transfer characteristics from a rotating circular cylinder kept in cross-flow is performed. The interaction between inertial and thermal forces strongly affects the wake of the circular cylinder. To study this interaction, the cylinder is kept in a cross flow corresponding to Reynolds number in the range of 50 to 200, and is heated so that the Richardson number is 1. The rotation rate is varied between 0 to 2, and its effect on wake was studied. It was found that with increase in rotation rate the variation of average Nusselt along the cylinder surface becomes more uniform. This uniformity is achieved on behest of reduction in heat transfer which can be attributed to the negative vorticity generation due to rotation of the cylinder. [ABSTRACT FROM AUTHOR]

A recent method of energy test for refrigerator requires two temperature test condition and lower airspeed of the temperature chamber. The testing technology laboratory of the Indonesian Institute of Sciences has developed a temperature chamber capable of conducting the test. This paper presents the heat transfer characteristic of the proposed configuration for heat exchanger for temperature chamber design. An aligned and staggered configuration is investigated in the current study as the proposed configuration of the heat exchanger through numerical modelling. Three parameters of heat transfer characteristics are determined in this current paper: heat transfer rate, heat transfer coefficient, and pressure loss. The result shows that the staggered results in higher heat transfer rate and heat transfer coefficient. Such greater heat transfer values may occur since the greater amount of bank for staggered configuration, and thus provide a greater area for fluid behavior. The verification model indicates a far gap at around 75% relative to the theoretical determination. The growth rate of 1.1 in the mesh sizing is not enough to provide a small sizing that may be indicated as a factor to such a considerable gap. The implication of the greater heat transfer space in staggered configuration brings to the concern of energy consumption for fan-speed as a result of greater pressure loss. The energy need for fan speed for staggered configuration is 1.66% higher of aligned configuration. [ABSTRACT FROM AUTHOR]