Effect Of Coolant Temperature Research Articles

Ice morphology modification and solute recovery improvement by heating and annealing during block freeze-concentration of coffee extracts

Several treatments on ice blocks can be applied during block freeze-concentration to increase the solute recovery from the ice. In the present study, the changes in the ice block’s temperature and the application of annealing during the block freeze-concentration of aqueous coffee extracts were studied. The ice block was subjected to heating and annealing prior to the thawing stage. The effect of coolant temperature during ice block heating (T = −10 and −5 °C) and the application of annealing (+, −) on solute recovery and ice structure morphology was evaluated. The use of annealing during block freeze-concentration modified the ice crystal morphology and increased the solute recovery only when it is applied at the highest temperature. In general, the annealing process increased the size and circularity of the ice crystals, consequently improving the solute recovery. Thus, annealing can be used to increase the solute recovery during block freeze-concentration.

Effect of coolant temperature on air–fuel mixture formation and combustion in an optical direct injection spark ignition engine fueled with gasoline and butanol

Diversification of the energy mix and the drive for increasing security of supply have extended the use of alternative fuels in internal combustion engines. Butanol is a viable energy source for spark ignition (SI) power units featuring higher energy density and compatibility with existing systems. The present work investigated the use of n-butanol in an optically accessible wall guided direct injection SI engine, operated at low load, as well as wide open throttle. Engine speed and injection pressure were kept constant, while coolant temperature was alternated between two values, so as to simulate cold-start and fully warmed-up conditions. In-cylinder pressure and exhaust gas emission measurements were coupled with optical results obtained through UV–visible flame visualization and 2D chemiluminescence. This allowed a more detailed insight into the occurrence of diffusive flames near the piston surface and an analysis of flame front propagation, as well as its morphology. The correlation of thermodynamic data and flame imaging with band-pass filters for recording the spatial distribution of the OH radical, soot precursors and carbonaceous structures gave information on the evolution of chemical species during combustion. While at low load the alcohol performed slightly better compared to gasoline, at wide open throttle the opposite was recorded. The effect of coolant temperature was more evident for butanol. These observations were correlated to the presence of liquid fuel film on the piston crown, which resulted in slower flame propagation and higher related emissions for the alcohol.

Monte Carlo Simulation of Inclined Reactivity Control Rod and Boron Poisoning for the Canadian-SCWR Supercell

The Canadian-SCWR is a heavy-water moderated supercritical light-water-cooled pressure tube reactor. It is fueled with CANada deuterium uranium (CANDU)-type bundles (62 elements) containing a mixture of thorium and plutonium oxides. Because the pressure tubes are vertical, the upper region of the core is occupied by the inlet and outlet headers render it nearly impossible to insert vertical control rods in the core from the top. Insertion of solid control devices from the bottom of the core is possible, but this option was initially rejected because it was judged impractical. The option that is proposed here is to use inclined control rods that are inserted from the side of the reactor and benefit from the gravitational pull exerted on them. The objective of this paper is to evaluate the neutronic performance of the proposed inclined control rods. To achieve this goal, we first develop a three-dimensional (3D) supercell model to simulate an inclined rod located between four vertical fuel cells. Simulations are performed with the SERPENT Monte Carlo code at five axial positions in the reactor to evaluate the effect of coolant temperature and density, which varies substantially with core height, on the reactivity worth of the control rods. The effect of modifying the inclination and spatial position of the control rod inside the supercell is then analyzed. Finally, we evaluate how boron poisoning of the moderator affects their effectiveness.

Effect of Coolant Temperature and Circulation Flowrate on the Performance of a Vertical Finned Crystallizer

Performance of a newly developed freeze concentrator named vertical finned crystallizer (VFC) in concentrating glucose solution was evaluated. The VFC was designed as an attempt to provide an efficient progressive freeze concentration (PFC) system by providing larger heat transfer area for crystallization. Glucose solution at an initial concentration of 11°Brix was concentrated through the new PFC system. The performance of the crystallizer was analysed in parallel with the effect of coolant temperature and circulation flowrate to the system efficiency, represented by effective partition constant (K) and solute recovery (Y). The results show that the efficiency of the system has significantly improved portrayed by the lowest K value obtained of 0.383 and the highest Y value obtained of 0.96g glucose/g initial glucose at intermediate coolant temperature and higher circulation flowrate. Thus, the VFC is evidently proven to have a high potential to be integrated in a PFC process as an efficient concentration system. The results obtained offer some guidelines on how to produce an efficient PFC system through parameter setting.

Effect of Coolant Temperature on Core Power Behavior of a Miniature Neutron Source Reactor

Published date: Investigation shows that reactor core performance largely depends on the power. It was in recognition of the role of this importance parameter that measurements were performed to verify the effect of temperature on core power of the Nigeria Research Reactor–1 (NIRR-1), which is Miniature Neutron Source Reactor (MNSR). Our results show that the core power for a preset neutron flux of 5.0×1011 cm-2s-1 shows a fluctuating behaviors and the values ranges from 14.85 kW to 15.09 kW with average excess reactivity of 3.07 mK and 2.99 mK respectively. The power coefficient off reactivity was also found to be (0.113 mK/kW and 0.114 mK/kW) with an average coolant temperature difference of 12.2 °C. The results also indicate the need to obtain a correction factor for samples that will stay in the reactor for cyclic or longer period of irradiation provided there will be shutdown and start-up in-between the irradiations and also addition of beryllium shim to the reactor is necessary in order to compensate for the loss of core excess reactivity. Our results also revealed that there is a strong dependence of the reactor power on coolant temperature difference, which is in perfect agreement with the design of the MNSR and findings of many workers in the area. The computer program developed in this work for the determination of core power using moderator parameters will not only serve as a new source code for microcomputer control of the reactor peak power and flux distribution but will also make it possible for the microcomputer console to display real time core power level, thermal limitation of the reactor core, a tool that is lacking in MNSR design.

Effect of Coolant Temperature on Progressive Freeze Concentration of Refined, Bleached and Deodorised Palm Oil based on Process Efficiency and Heat Transfer

In this paper, raw material of refined bleached and deodorised palm oil (RBDPO) was separated into olein and stearin by applying progressive freeze concentration (PFC) as an alternative method to replace the conventional fractionation process using coil crystallizer. Overall heat transfer coefficient (U) was analyzed from the process by varying different coolant temperature values since both of them are closely related each other. In this case, heat transfer efficiency depends strongly on crystal of stearin formed on the inner wall of cooled surface and is explained theoretically from that angle. At optimum flowrate, operation time and initial iodine value (IV), the best results were observed at 28ºC of coolant temperature where high IV of olein and effective partition constant (K) obtained were 55.8 wijs and 0.27 respectively. Meanwhile, the highest U obtained at coolant temperature 28oC same as result for process efficiency at 392.9183 W/m².K and time at 55 min.

Progressive Freeze Concentration of Coconut Water: Effect of Coolant Temperature on Process Efficiency and Heat Transfer

In this research, coconut water was concentrated by applying progressive freeze concentration (PFC) using coil crystallizer. Overall heat transfer coefficient (U) was analyzed from the process by varying different coolant temperature values since both of them are closely related. In this case, heat transfer efficiency depends strongly on ice crystal formed on the inner cooled surface and is explained theoretically from that angle. At optimum flowrate, operation time and initial concentration best results were observed at-10oC of coolant temperature where the concentration efficiency and effective partition constant (K) obtained were 48% and 0.2 respectively. Meanwhile, U obtained at the first and second stages were 183.0046 W/m2oC but dropped at lower value at later stage at 154.9625 W/m2oC due to ice fouling.

Effect of Coolant Temperature on Desalination Process via Progressive Freeze Concentration

The world is still suffering from a shortage of clean water supply and the problem is expected to become more serious in the future. Consequently, researchers have been trying to find the best solution to address this problem by introducing new desalination technologies that are able to accommodate the demand for clean water which is increasing from time to time. One of the new technologies introduced is the desalination of seawater through freeze concentration. In this study, progressive freeze concentration (PFC) is implemented to produce pure water in the form of ice crystal block and leave behind a higher concentration solution. The effect of coolant temperature was investigated and the efficiency of the system was reviewed based on the value of effective partition constant, K which is defined by the ratio of solute in ice and liquid phase. The low value of K leads to the best efficiency for the system. Apart from that, the efficiency, E% and salinity reduction were also calculated in order to determine the system performance.

Exhaust Emission Characteristics of Heavy Duty Diesel Engine During Cold and Warm Start

Through experiment conducted on a six cylinder direct injection diesel engine with SCR catalyst, effects of coolant temperature on rail pressure, injection quantity, excess air coefficient and emissions characteristics during cold and warm start were investigated. The results showed that, the maximum injection quantity during a starting event was several times higher than idling operation mode, so was the maximal opacity in the cold and warm starting process. When coolant temperature rose up to above 20℃, NO X emissions in the starting process exhibited peculiar rise which was times higher than idling mode. Compared with engine warm start, rail pressure, cycle fuel quantity, opacity, CO and HC emissions during engine cold start were higher in the course from their transient maximal values towards stabilized idling status. NO X in the same transient course, however, were lower in cold start. As coolant temperature rose, the maximal and the idling value of rail pressure and cycle fuel injection quantity during diesel engine starting process decreased gradually, the excess air coefficient increased to a certain degree, and the maximal and idling values of NO X increased gradually.

Effect of Coolant Temperature on Progressive Freeze Concentration of Refined, Bleached and Deodorised Palm Oil

This study focused on the possibility of separating refined, bleached and deodorized palm oil (RBDPO) into olein and stearin by using progressive freeze concentration (PFC) as an alternative method to replace the conventional fractionation process. PFC has the potential to be a more effective technique for olein-stearin separation, with minimal changes in the product’s quality for producing high quality edible oil. Apart from that, it requires fewer unit operations compared to conventional methods. In this research, the parameter of coolant temperature was selected to investigate the performance of PFC using stainless steel crystallizer. In order to determine the system efficiency, effective partition constant (K) was investigated, while the quality of the oil was evaluated by iodine value (IV), slip melting point (SMP) and the percentage of olein yield. From the results, all the determinant parameters were found to be optimum at the coolant temperature of 28°C. At this optimum point, K value, IV, SMP and olein yield were found to be 0.2715, 55.84 wijs, 23.10°C and 67.8537%, respectively.

Study on Thermal Influence of Grinding Process on LiTaO<sub>3</sub>

As a typical multi-functional single crystal material, Lithium tantalate (LiTaO3 or LT) exhibits its excellent electro-optical, pyroelectric and piezoelectric properties, and has now been widely applied into many applications, especially in the telecommunication field. However, the most critical issue in the process is its pyroelectric effect and piezoelectric effect which potentially leads to crack initiation during grinding. Because it is rich in plasticity, LT demands larger specific energy for material removal. As the most machining energy is eventually converted into heat, LT undergoes a rapid rise in temperature during the grinding process, thus highly risks in thermal shock. In order to clarify the thermal influence on the grinding process of LiTaO3, the effects of coolant temperature, diamond grinding wheel geometry and material of substrate are investigated in this research. The experimental results show that the increasing rate of grinding torque (or force) and surface roughness are two major factors dominating the crack initiation during grinding of LT wafers. Via a DOE (design of experiment) analysis, coolant temperature and wheel type stand out as the main factors influencing on the increasing rate and wafer surface roughness.

Process Optimization of Effective Partition Constant in Progressive Freeze Concentration of Wastewater

Response surface methodology (RSM) was employed to optimize the process parameters for effective partition constant (K) in progressive freeze concentration (PFC) of wastewater. The effects of coolant temperature, circulation flowrate, initial solution concentration and circulation time on the effective partition constant were observed. Results show that the data were adequately fitted into a second-order polynomial model. The linear and quadratic of independent variables, coolant temperature, circulation flowrate, initial solution concentration and circulation time as well as their interactions have significant effects on the effective partition constant. It was predicted that the optimum process parameters within the experimental ranges for the best K would be with coolant temperature of -8.8°C, circulation flowrate of 1051.1 ml/min, initial solution concentration of 6.59 mg/ml and circulation time of 13.9 minutes. Under these conditions, the effective partition constant is predicted to be 0.17.

Effect of Coolant Temperature on the Condensation Heat Transfer in Air-Conditioning and Refrigeration Applications

This article directly investigates the effect of a cooling medium's coolant temperature on the condensation of the refrigerant R-134a. The study presents an experimental investigation into condensation heat transfer, vapor quality, and pressure drop of R-134a flowing through a commercial annular helicoidal pipe under the severe climatic conditions of a Kuwait summer. The quality of the refrigerant is calculated using the temperature and pressure obtained from the experiment. Measurements were performed for refrigerant mass fluxes ranging from 50 to 650 kg/m2s, with a cooling water flow Reynolds number range of 950 to 15,000 at a fixed gas saturation temperature of 42°C and cooling wall temperatures of 5°C, 10°C, and 20°C. The data shows that with an increase of refrigerant mass flux, the overall condensation heat transfer coefficients of R-134a increased, and the pressure drops also increased. However, with the increase of mass flux of cooling water, the refrigerant-side heat transfer coefficients decreased. Using low mass flux in a helicoidal tube improves the heat transfer coefficient. Furthermore, selecting low wall temperature for the cooling medium gives a higher refrigerant-side heat transfer coefficient.

Effect of coolant temperature on combustion and combustion noise fluctuations in a Diesel engine at idle conditions

At idle conditions, the cycle‐to‐cycle fluctuations in Diesel engines lead to combustion noise variations that could be annoying for people, even if the mean level is low, and the cold start condition is one of the worst cases. This study focuses on the effect of injection parameters (duration and timings) and the effect of coolant temperature on combustion characteristics and on the combustion noise. A Direct Injection Diesel engine (four cylinders, 16 valves) equipped with a common‐rail injection system and piezoelectric injectors was used. The coolant temperature is changed at idle from the ambient temperature to the temperature at normal working conditions. The combustion is analysed in terms of rate of heat release and combustion noise through the measurement of the cylinder pressure. The results show the dependency of the combustion behavior on the increase of coolant temperature at constant engine adjustment parameters. It is also shown that acting on adjustment parameters can modify the combustion behavior and, consequently, the cycle‐to‐cycle fluctuations. A trade‐off between combustion noise and engine emissions can thus be reached.

Aerodynamic loss prediction of axial flow turbine blade rows with coolant injection

This work presents a calculation routine for the prediction of the aerodynamic loss of axial flow turbines with coolant injection, which can be easily incorporated into throughflow calculation programs. The concept of the mixing layer is introduced and the one-dimensional method is used to estimate the local mixing pressure loss. For a real annular nozzle guide vane, calculations are performed with the aid of the mixing model and viscous loss correlations in order to predict loss at the blade mid-height. Predictions for various single-row configurations show favourable agreement with experimental results. Losses are also calculated for the multi-row configuration with a consideration of flow recirculation among cooling holes. It is found that the coolant recirculation may cause a considerable increase in the pressure loss when the amount of net coolant supplied is relatively small. The effect of coolant temperature is also examined for both single-row and multi-row cases.

グラニュラー・アイス方式冷熱貯蔵 クーラントの粘性効果

The granular-ice making method for cool-heat storage has been experimentally investiguted. Granular-ices were formed through injecting water droplets into a low temperature immiscible coolant whose specific gravity is smaller than water. As a low temperature immiscible coolant, kerosine or mixture of kerosine and engine oil has been utilized, where oil concentration was ranged from 0 to 40% in volume. It was found that the granular-ice can be successively produced even at -5°C. Above at -5°C, the ice-bridging phenomenon occurred for any concentration measured. Optimum conditions for succesive production of granular-ice were obtained as follows. 1) circulation of the mixture of kerosine and engine oil, and 2) no circulation of kerosine only. The effect of coolant temperature and viscosity on the successive production of granular-ices were discussed.

Effects of coolant temperature and pump power on the power output of solar-pumped solid state lasers

The temperature dependence of solar-pumped solid state lasers of Nd:YAG and two types of Nd:Cr:GSGG was studied over the temperature range of +30 to -60°C in a quasi-cw mode. All lasers had higher output powers at -40°C. The Nd:Cr:GSGG laser with a chromium concentration of 2.5 at. % produced 70 W of power at -40°C, quasi-cw. If extrapolated to true cw operation this is equivalent to 350 W. The temperature dependence of the laser performance is attributed to changes in both the stimulated emission cross section and the resonator configuration.