Coolant Fluid Research Articles

Experimental Investigation on Single-Phase Immersion Cooling of a Lithium-Ion Pouch-Type Battery under Various Operating Conditions

The selection of a battery thermal management technique is important to overcoming safety and performance problems by maintaining the temperature of batteries within a desired range. In this study, a LiFePO4 (LFP) pouch-type battery having a capacity of 20 Ah was experimentally cooled with both air and liquid (immersion cooling) techniques. Distilled water was selected as the immersion fluid in the experiments, and the impact of discharge rate (1–4C), immersion ratio (50–100%), and coolant fluid inlet temperature (15–25 °C) on the battery temperature were investigated during the discharge period. The experiments revealed that maximum temperatures were reached at approximately 45 °C and 33 °C for air and distilled water cooling techniques, respectively, at the discharge rate of 4C. The average and maximum battery surface temperatures can be reduced by 28% and 25%, respectively, with the implementation of the liquid immersion technique at the discharge rate of 4C compared to the air technique. Moreover, the experiments demonstrated that the maximum temperature difference could be lowered to 4 °C by means of 100% liquid immersion cooling at the highest discharge rate, where they are approximately 11 °C and 12 °C for air and 50% for immersion cooling, respectively. In addition, it was observed that the coolant fluid inlet temperature has a significant impact on battery temperature for %100 liquid immersion.

Energy harvesting from liquid cooling systems using thermo-electrochemical flow cells

We report a flow thermocell that is integrated into liquid cooling systems to convert the temperature difference between hot and cold pipes into electrical energy. This flow thermocell uses porous Ni foam electrodes that are inserted into the pipes carrying heated and cooled fluids. An aqueous ferricyanide/ferrocyanide electrolyte is used as a coolant fluid to generate electricity through thermally driven redox reactions on the electrodes. The power generation capability of the fabricated device is evaluated for operating conditions. As the flow rate of electrolytes having a temperature difference of 22 °C increase from 0.3 to 1.5 mL/s, the power density increase from 0.129 to 0.208 mW/cm2 owing to the reduction in the mass transport overpotential for power generation, and a Carnot-relative efficiency of 0.304% is obtained at an optimal flow rate of 1.2 mL/s. The efficiency can be further increased to 0.50% by reducing the heat loss from heated to cooled electrolytes with increasing the inter-electrode spacing. The efforts provide here to optimize the design and performance of flow thermocells would be useful in devising new active cooling systems that incorporate the ability to harvest heat flow in liquid cooling systems into electrical energy while simultaneously performing liquid cooling.

Method of heat transfer magnification by utilization of perverted tape with working substance water

Heat exchanger is a fundamental component of intensity and refrigeration cycles. These cycles encourage the exchange of vitality from a specific way to other depending on the righteousness of temperature contrast. Within a heat exchanger, there is change in the temperature of the liquid that flows through the exchanger, which results in the fluctuation of the divider’s temperature owing to the flow of liquid through the exchanger. Heat exchanger is capable of shifting the heat from the hotter to the cooler fluid, thereby managing the heat present within the framework. Therefore, the proposal is to quickly change the ideal measure of warmth vitality. The inventers of heat exchanger quickly formulated a productive and smaller heat exchanger at a nominal expense. For enhancing warmth movement, two strategies have been designed; one is a functioning strategy that needs an outside power source; and the other is an aloof technique with no need for outer power source. The change of heat transfer has been observed for numurous kinds of perverted tape geometries with the twist ratios of 2.5, 3 and 3.5 by changing the Re in the span of 4000 to 15000.

Origin of the Amensif Zn-Cu (Pb-Ag-Au) distal skarn deposit (Western High Atlas, Morocco): Constraints from C-O-S isotopes

The Amensif Zn-Cu (Pb-Ag-Au) ore deposit is located in the northern part of the western High Atlas. The deposit hosts 1 million tons (Mt) of Zn-Cu-Pb metal reserves at 3% Zn, 2% Cu, and 1% Pb. The lenticular sulfide ores are structurally controlled open-space fillings (fractures, faults) in the Lower Cambrian carbonates. The mineralogical paragenetic sequence consists of andradite-quartz-epidote-dolomite-calcite-sphalerite-chalcopyrite-pyrite-galena with subordinate amounts of barite. The pre-ore stage and ore stage I dolomite samples have δ13CPDB and δ18OSMOW values in the range of −10.2 to −2.6‰ and 17.4–26.8‰, respectively. The lower δ18O value of these dolomites suggests oxygen isotope exchange between the ore-forming fluids and the carbonate host rock whereas negative δ13CPDB values reveal the interaction between these hydrothermal fluids and black shales. The δ34S values of sulfides ore (sphalerite, chalcopyrite, and pyrite) are high, ranging from 6.4 to 14.4‰. These S isotopic values reveal that sulfur derived from the mixture of magmatic sulfur and lower Cambrian carbonate-derived sulfur in almost equal proportions. Sulfide ores precipitated from the mixing between the magmatic-hydrothermal fluids exsolved from a hidden magma or the nearby Azegour granite of Permian age and an external cooler fluid of unknown origin. Fluid-rock interactions with the carbonate host rock contributed in the precipitation of the ore. Mineralogical and geological features allow us to ascribe the Amensif Zn-Cu (Pb-Ag-Au) polymetallic ore as a distal skarn system which is spatially associated with the lower Permian granite intrusion.

Pengaruh Variasi Fluida Pendingin Terhadap Laju Pendinginan Engine Yamaha Nmax

Radiator is a cooling system using fluid as a heat exchanger. How the radiator works by channeling the heat released by the motor engine is then absorbed by the radiator coolant fluid. The radiator device consists of a coolant inlet and engine outlet, a cooling fan mounted in front or behind the radiator, and coolant. Coolant in the radiator has a very important role in dissipating engine heat to the environment. In this study, I will analyze the different types of coolant variations, namely water, prestone antifreeze, Seiken, premix coolant DCK, and yamacoolant. on the cooling rate and radiator effectiveness using rotation variations of 1600, 3000,5000 rpm and measurement times of 1, 5, and 10 minutes on the Yamaha Nmax engine. The results of the research that have been carried out are the average heat transfer rate and the highest radiator effectiveness occur in the Yamacoolant type cooling fluid of 1.992kW and 0.726, the second highest occurs in the Prestone cooling fluid where the heat transfer rate value is 1.918kW and the radiator effectiveness is 0.652, then followed by Seiken where the heat transfer rate is 1.901kW and the radiator effectiveness is 0.634, then followed by DCK the heat transfer rate is 1.702kW and the radiator effectiveness is 0.592 and the smallest is experienced by mineral water where the heat transfer rate is 1.542kW and the radiator effectiveness is 0.501.

Role of Insulation Materials and Cryogenic Coolants on Fault Performance of MW-Scale Fault-Tolerant Current-Limiting Superconducting Transformers

Fault-tolerant current-limiting (FTCL) high-temperature superconducting (HTS) transformers are promising components for playing a role in renewable energy integrated modern power systems. In this article, the impact of different insulation materials and cryogenic coolant fluids on the electro-thermal characteristic of an MW-scale FTCL-HTS transformer is investigated. For this purpose, an equivalent circuit model (ECM) is established to characterize the temperature, recovery time, and fault tolerability of FTCL-HTS transformer under different conditions. The proposed ECM is firstly validated using experimental results of a typical HTS transformer. After that the model is developed for a 50 MVA, 132 kV/13.8 kV HTS transformer. In order to add fault tolerance capability to the 50 MVA HTS transformer, three strategies were considered in this article. In the first strategy, the effect of three insulation materials (including Kapton tapes, Nomex papers, and Acrylated Urethane solid insulation) covering HTS tapes was investigated on fault performance. The second strategy was changing cryogenic fluid to liquid hydrogen instead of liquid nitrogen. As for the last strategy, the impacts of thickness and material properties of stabilizer in HTS tape were investigated on the maximum temperature and recovery time of HTS transformer. Results show that by using these strategies, the maximum temperature of HTS tape of transformer winding under a short circuit fault was reduced.

Exceptional preservation of organic matter and iron-organic colloidal mineralization in hydrothermal black smoker-type sulfide mineralization from the Paleoarchean seafloor

Fossil organic matter (OM) in Paleoarchean rocks is an invaluable tracer of ancient life, yet it is often contentious due to low preservation potentials of its original organic molecular characteristics under generally high metamorphic grades. This study reports on exceptionally preserved OM within black smoker-type sulfide mineralizations from the 3.24 billion-years-old Sulphur Springs volcanic-hosted massive sulfide deposit, East Pilbara Terrane, northwestern Australia. Fine scale mineralogical and organic molecular variations – documented by SEM and TEM techniques, Raman and FTIR Spectroscopy, as well as ToF-SIMS analysis – trace the formation of millimetre-scale pyritic hydrothermal orifices. Overmature OM (≳200–250 °C) enriched in aromatic hydrocarbons occurs within earliest formed colloform-banded pyrite that could have precipitated at high temperature upon mixing of hot hydrothermal fluids with cold seawater. In contrast, mature OM (within the catagenesis window; ∼100–150 °C) with lower proportions of aromatic hydrocarbons occasionally occurs alongside pyrite within barite near the inner paleofluid conduits of the hydrothermal orifices. A deposition of this OM generation from cooler fluids enriched in sulfate during waning hydrothermal activity is corroborated by its association with original mineralogy, particularly the occurrence of isolated nanoinclusions of OM within hydrothermal barite away from grain boundaries or fissures and cracks, which renders impossible an origin from post-depositional hydrocarbon migration. When compared to the overmature OM within colloform-banded pyrite, the better-preserved inner OM not only contains less abundant, smaller, and less ordered aromatic hydrocarbons, but also higher amounts of aliphatic molecules with longer chain lengths and higher proportions of carbonyl and amide functional groups. Although the latter characteristics are consistent with contributions by microbial biomass, abiotic origins are equally plausible because hydrothermal processes can produce OM with similar organic molecular attributes. Irrespective of these uncertainties on the ultimate sourcing of OM, common intergrowths of the cooler OM with nanoscopic iron oxides – hematite and lesser magnetite – hint at its hydrothermal deposition from colloidal particles that have been stabilized by iron-organic complexation. Further research is required to ascertain the significance of this process for the hydrothermal cycling and release of organic carbons and bound iron into the Paleoarchean oceans. Collectively, our results show that ancient marine hydrothermal systems can preserve OM with differing degrees of thermal degradation, which allows for insights into its sourcing, cycling, and deposition.

Numerical Investigation of Cooling an Industrial Roller by Using Swirling Jets

Effective cooling of industrial rollers has prime importance to prevent the quality degradation of the system and product. High temperature difference on the roller surface may result in thermal stresses and can cause deformations on roller surface and product. In order to prevent these deformations, cooling of an industrial roller by using swirling jets is investigated for different parameters numerically in this study. Effects of Reynolds number, surface heat flux and variation in inlet temperature of the fluid on the performance of an industrial roller are investigated in terms of temperature difference between inner and outer surface of the roller. ANSYS Fluent CFD program is used to simulate heat transfer and fluid flow in this numerical study. As a result, it is obtained that increasing Re number from 1000 to 1700 causes a decrease of 45.4% in the temperature difference between inner and outer surface of the roller. Increasing surface heat flux from 5000 to 12500 W/m2 has resulted in an increase of 149.4% in difference between inner and outer surface temperature. Increasing coolant fluid inlet temperature from 5 to 20°C has resulted in an increase of surface temperature but there is no significant change in heat transfer characteristics of the system. It is evaluated that the results of this study will contribute to design more effective cooled industrial roller.

Heat transfer and flow characteristics in symmetric and parallel wavy microchannel heat sinks with porous ribs

Based on the synergistic design concept, double-layered microchannel heat sinks with parallel and symmetric wavy porous fins are developed with the desire to simultaneously attain pressure drop reduction, heat transfer enhancement, and cooling uniformity improvement. Using a 3D fluid-solid conjugate model, the hydrodynamic and thermal details are numerically studied to compare two wavy configurations with the solid- and porous-fin designs. The results demonstrate that for wavy microchannel heat sinks, the porous-fin design can significantly enhance heat transfer performance and reduce pressure drop. The symmetric configuration yields a higher pressure drop reduction, whereas the parallel one provides a higher increment in thermal performance. As a result, using the porous design, two wavy configurations have nearly the same level of pressure drop penalty, but the parallel configuration contributes to higher thermal performance. The decreased flow rate of the channel due to the permeation of coolant fluids into porous ribs and the slip effect on the channel wall contribute to the pressure drop reduction. The permeation effect of coolant greatly restrains secondary flow characteristics induced by wavy walls which are responsible for the enhanced coolant mixing in conventional heat sinks. Consequently, the increased inlet flow velocity at a constant pumping power contributes to the improved thermal performance, namely the reduced thermal resistance and the increased Nusselt number. With a stronger coolant permeation owing to the jet-like impingement flow, the parallel configuration yields a slightly lower thermal performance compared to the symmetric configuration in the new design. Finally, the parametric analysis at a fixed pumping power is further carried out for optimizing the proposed design.

Coolant circulation improvement on the chip tub of the machine lnc okuma 0002 pt. komatsu undercarriage indonesia

In general, coolant is a cooling medium used to cool workpieces and cutting tools during the machining process. In PT Komatsu Undercariage Indonesia, the LNC OKUMA 0002 chip crankcase contained a lot of stagnant coolants. The factor that causes the coolant to stagnate is that the growl is wasted through the chip conveyor and the coolant is carried along with the growl to the chip. Changing the coolant fluid needs to be done in a certain phase because the use of the coolant for too long causes sand to accumulate. Excessive sand can close the cooling duct system. The quality of the coolant can deteriorate due to heat and a dirty environment. In addition, corrosion on the radiator can also result in the deposition of dirt on the coolant. When this happens, the engine overheats easily and triggers a stall. The repairs that have been carried out are examining and repairing the components of the coolant system by adding a coolant channel and a pump that functions to suck the coolant so that the coolant returns to the LNC OKUMA 0002 engine.

Heat Transfer and Flow Characteristics of Coal Slurries under the Temperature Difference between Inside and Outside of the Channel

The pipeline transportation of coal slurries is always subject to a temperature difference between the outdoors environment and the fluid body. As slurries’ viscosity is typically temperature dependent, the flow is accompanied by the heat transfer. In this study, we used the CFD method to investigate temperature distributions and flow structures in straight and curved channels, which has not previously been investigated, according to our knowledge. First, the results demonstrate that the cooling process influences the flow structures along the stream. The fluid turns more sharply in the cooler fluid in the curved channel, the streamlines overlap at an earlier position within the bend, and the velocity maximum zone is wider. Cooling also has a significant impact on transverse flow. Because of the higher viscosity of the more cooled fluid and thus the difficulty of shearing the fluid in the stream-wise direction, the vorticity and strength of the vortex flow are greater. The fluid velocity at the central part of the channel points toward the inner wall at the beginning of the bend, resulting in an inner-wall biased temperature distribution, as the heat transfer is partially carried out by the fluid velocity. The central velocity points toward the outer wall at the end of the bend, resulting in the outer-wall biased temperature profile.

The value of heat and geothermal waters

Evaluation of proposed geothermal projects often requires a value to be assigned to waterborne geothermal heat or geothermal fluids. A methodology for valuing low-enthalpy warm fluids (<90°C) is presented: the method uses a reference price for sale of waterborne district heating at a relatively high temperature (in this paper, we have assumed 70°C), and then discounts this price by the value of electricity that must be expended in a heat-pump compressor to transfer heat from the source fluid to the target reference level. An alternative methodology is also presented, based on the exergy content of the geothermal fluid: this is arguably more theoretically justifiable but does not account for the real costs of running a heat pump. Compared with other sources of low-carbon environmental heat, prospecting for deeper warm geothermal fluids will be favoured when drilling costs are low and electricity prices are high; shallow cooler fluids, coupled with the use of heat pumps, are economically favourable when electricity is cheap and drilling costs are high.

Computational assessment of the thermal response of a Li-ion battery module to transient loads

This paper provides a methodology to assess the average surface temperature of battery cells under realistic transient scenarios. Computational fluid dynamics modelling of battery cooling is conducted for the cases exposed to the ramps of internal heat generation inferred from the standard driving cycles. The results are then post-processed to determine the effectiveness of air and water as the coolant fluids. A quantitative measure of the maximum overshoot, dimensionless settling (DST), heating (DHT), and cooling (DCT) time is subsequently presented. It is shown that, compared to water, air produces a considerably delayed response to temporal changes in the internal heat generation and is slower at reaching the new steady state condition. Cooling battery cells by using water almost always ensures remaining within the safe operating range. Nonetheless, regardless of the coolant type, the long period ramps tend to produce smaller values of DST. The primary origin of the delay is the slow heat conduction within the battery cells. In addition, it is shown that water responds to changes in the internal heat generation far quicker during the heating and the cooling phases. The study highlights the importance of transient analyses for characterising the thermal behaviour of battery packs.

Thermal Management Performance of Lithium-Ion Battery Using Supercritical CO2 as Cooling Fluid

Thermal management system is very crucial to guarantee the safe and high-efficient operation of lithium-ion batteries, and different kinds of medium, such as air, water and phase change material, can be adopted in thermal management systems. However, these mediums are still less than satisfactory when it comes to the stressful conditions. In this study, a new medium - supercritical CO2 is proposed to be used in controlling the temperature of lithium-ion batteries. Numerical simulations are conducted to investigate the feasibility and superiority of supercritical CO2 as the thermal management medium. The effects of inlet parameters of supercritical CO2 on the cooling performance are studied, and the underlying mechanisms for the superiorities of supercritical CO2 are revealed. The results indicate that supercritical CO2 around the critical point possesses the combined benefits of phase change material and liquid medium, making it a prominent medium for battery thermal management system. The superiorities of supercritical CO2 mainly originate from the large specific heat region around the pseudocritical point, and these advantages endow supercritical CO2 excellent capabilities coping with stressful conditions, such as high discharging rates and scorching weather.

Heat exchangers with fluidization of bulk material (Design review)

A classification of heat exchangers with fluidization of bulk material for use in enterprises of the chemical, mining, construction, food, metallurgical and processing industries has been developed. A critical review of the most characteristic designs of heat exchangers with a fluidized bed, proposed by scientists, designers and inventors of the leading countries of the world, has been carried out. The designs of heat exchangers are analyzed depending on the method of fluidization, the role of bulk material in the heat exchange process, the nature of the heat exchange process over time, the nature of fluidization (in continuous heat exchangers), the mechanism of heat exchange of bulk material, the number of fluidized beds, the presence of additional heat exchange devices in the heat exchanger, the presence of movable structural elements, as well as the type of bulk material of the fluidized bed.
 An analysis of the designs of heat exchangers with a fluidized bed indicates their considerable diversity, however, the most simple to manufacture and operate reliable devices with fixed structural elements and one fluidized bed remain in demand by the industry. The most promising direction for improving fluidized bed heat exchangers is the development of specialized (for processing bulk material or fluid coolant) designs of apparatuses.
 In the future, it is planned to analyze the designs of other types of heat exchangers, as well as ways to improve their efficiency.

Effect of Velocity and Type of Cooling Fluid on Peltier Heat Transfer for Car Cabin Cooling Applications

This research used the Peltier element as a car cabin cooler. This research aimed to compare the results of the lowest temperature produced by the Peltier element on the hot side. The design of this monitoring tool consists of LM35 as a temperature sensor and an electric velocity sensor to measure the velocity of the cooling fluid. Arduino Uno Microcontroller to control the system before being displayed to the LCD. The type of research used in this research is experimental research. In this study, variations in fluid flow velocity and type of cooling fluid were carried out. The fluid used is a mixture of water and water coolant with a ratio of 50%:50%. The results showed that the circulation of fluid cooling influences the temperature on the hot side of the Peltier. In cooling using water fluid, when the water pump rotates 4.5 liters/second, the temperature on the hot side of the Peltier is 36ᵒC. At the time of rotation of 13 liters/second, the temperature on the hot side of the Peltier is 32ᵒC. The difference between cooling using water fluid, water coolant, or a mixture of water and water coolant greatly affects the temperature produced on the cold side of the Peltier. In cooling using water, the lowest temperature produced reaches 8ᵒC. When the cooling using a fluid coolant, the lowest temperature reaches 6ᵒC. While cooling using a mixture of water and coolant, the lowest temperature reaches 3ᵒC. So it can be concluded that cooling using a mixture of water and water coolant is very effective compared to other fluid coolers.

Water-based Cooling Fluids to Mitigate the Thermal Management Challenges in New Energy Vehicles

Thermal management is considered one of the key enablers for the adoption of New Energy Vehicles. An efficient design of an electrified vehicle’s cooling system, be it a HEV, BEV or FCEV, is of major importance to guarantee vehicle lifetime, optimize energy efficiency, enable adequate driving range and allowing high charging speed. Moreover, it is of critical importance for safety. Compared to internal combustion engine (ICE) vehicles, cooling systems for electrified vehicles have become more complex with increasing integration of a variety of parts. The cooling medium’s main function is no longer limited to cooling of the ICE; it also used to conserve and transport heat to essential powertrain parts such as the battery pack, all while electrical safety cannot be jeopardized. Many recently launched electrified vehicles successfully employ the same water-glycol based cooling liquids that are found in ICE vehicles. In light of future developments such as ultra-fast charging, advances in cooling systems and the cooling liquid are required. Recently, a clear shift from air cooling towards waterbased cooling fluids is witnessed mainly due to the strong beneficial heat transfer properties of water. For direct cooling of fuel cell stacks different changes are demanded since the upper electrical conductivity limit of the aqueous liquid compels the use of new additive technology.

Synthesis and application of ZnO rod-shaped nanoparticles for the optimal operation of the plate heat exchanger

ZnO nanoparticles with tunable morphology exhibit attractive behaviors in transport phenomena, which make them valuable for thermal applications. The present study focuses on the synthesis and application of ZnO nanoparticles with two different shapes for the preparation of the working heat transfer nanofluid. First, the rod-shaped and spherical-shaped nanoparticles were synthesized by simple chemical methods and then ultrasonically dispersed in pure water to prepare a set of stable nanofluids with concentrations between 0.2% and 1% of nanoparticles. The nanofluid samples were analyzed thermo-physically to obtain the optimal nanoparticles volume fraction for presenting the best thermal properties. In the following, a brazed plate heat exchanger was examined to evaluate the heat transfer characteristics of the selected nanofluids as a coolant fluid at flow rates between 1 and 3.5 l/min. The experimental results showed that the lowest Prandtl number appeared at the volume fraction of 0.4%. This concentration was considered the operating basis of the heat exchanger. ZnO nanoparticles had the considerable effect on the thermal characteristics of water as a working fluid. The maximum growth in the heat transfer rate was found for the nanofluid with the rod-shaped nanoparticles at the lowest flow rate (1 l/min), which were 29.2% more than pure water and 7.5% higher than the nanofluid with spherical-shaped nanoparticles. Additionally, due to the exponential increase in the pumping power, there was a flow rate range (less than 2 l/min) in which the energetic performance of the nanofluids was higher than water.

Analysis of activated colloidal crud in advanced and modular reactor under pump coastdown with kinetic corrosion

The analysis of rapid flow transients in Reactor Coolant Pumps (RCP) is essential for a reactor safety study. An accurate and precise analysis of the RCP coastdown is necessary for the reactor design. The coastdown of RCP affects the coolant temperature and the colloidal crud in the primary coolant. A realistic and kinetic model has been used to investigate the behavior of activated colloidal crud in the primary coolant and steam generator that solves the pump speed analytically. The analytic solution of the non-dimensional flow rate has been determined by the energy ratio β. The kinetic energy of the coolant fluid and the kinetic energy stored in the rotating parts of a pump are two essential parameters in the form of β. Under normal operation, the pump's speed and moment of inertia are constant. However, in a coastdown situation, kinetic damping in the interval has been implemented. A dynamic model ACCP-SMART has been developed for System Integrated Modular and Advanced Reactor (SMART) to investigate the corrosion due to activated colloidal crud. The Fickian diffusion model has been implemented as the reference corrosion model for the constituent component of the primary loop of the SMART reactor. The activated colloidal crud activity in the primary coolant and steam generator of the SMART reactor has been studied for different equilibrium corrosion rates, linear increase in corrosion rate, and dynamic RCP coastdown situation energy ratio β. The coolant specific activity of SMART reactor equilibrium corrosion (4.0 mg s−1) has been found 9.63 × 10−3 μCi cm−3, 3.53 × 10−3 μC cm−3, 2.39 × 10−2 μC cm−3, 8.10 × 10−3 μC cm−3, 6.77 × 10−3 μC cm−3, 4.95 × 10−4 μC cm−3, 1.19 × 10−3 μC cm−3, and 7.87 × 10−4 μC cm−3 for 24Na, 54Mn, 56Mn, 59Fe, 58Co, 60Co, 99Mo, and 51Cr which are 14.95%, 5.48%, 37.08%, 12.57%, 10.51%, 0.77%, 18.50%, and 0.12% respectively. For linear and exponential coastdown with a constant corrosion rate, the total coolant and steam generator activity approaches a higher saturation value than the normal values. The coolant and steam generator activity changes considerably with kinetic corrosion rate, equilibrium corrosion, growth of corrosion rate (ΔC/Δt), and RCP coastdown situations. The effect of the RCP coastdown on the specific activity of the steam generators is smeared by linearly rising corrosion rates, equilibrium corrosion, and rapid coasting down of the RCP. However, the time taken to reach the saturation activity is also influenced by the slope of corrosion rate, coastdown situation, equilibrium corrosion rate, and energy ratio β.

EFFECTS PARTICLES CONCENTRATION OF Al2O3 AND TiO2 TO CONVECTION COEFFICIENT ON DOUBLE PIPE HEAT EXCHANGER

Heat exchanger is a device used to transfer heat energy from a fluid to in another fluid. Each fluid has different characteristics. Value of convection heat transfer is determined by the value of the convection heat transfer coefficient (h) which depends on the dimensions and flow conditions. The fluid with the additional of Al2O3 nanoparticles (aluminum oxide) and TiO2 (Titanium dioxide) has great potential for cooling applications. The purpose of this study was to analyze the effect of Al2O3 and TiO2 particle concentration on the value of the convection heat transfer coefficient in the double pipe heat exchanger with circular straight pipes. Cooling fluid used is pure water, the fluid with the addition of Al2O3 nanoparticles and fluid with the addition of TiO2 nanoparticles at concentrations of respectively 40 ppm and 60 ppm. Flow used in a heat exchanger is the flow of counterflow type. Changes in temperature controlled 95 ° C for hot fluid, 17ºC for cooling fluid. The results show the influence of Al2O3 and TiO2 nanoparticles in the fluid characteristics and an increase in the value of the convection heat transfer coefficient is influenced by the amount of concentration on mixing nanoparticles in the cooling fluid.