In all the reactors, the hemispherical RPV lower head is more than enough to contain the whole molten core material. Note that the in-core instrumentation nozzles and other structural materials in the lower plenum are not considered in this calculation. The side area facing the RPV lower head is used to compute the downward heat flux from the debris. It was found that the sensible heat flux from the debris facing the RPV lower head is twice the decay heat flux of debris. The upper surface area can be utilized to determine the upward heat flux from the debris facing the steam-water mixture or the remaining core and the upper plenum structure above. If there exist pores and crevices within the solidified debris, the upward heat flux may increase. Quantitative analysis of intra-debris pores and crevices is not performed in this study, however. Rather, we concentrate on the single heat transfer mechanism in the debris-to-RPV annular gap limited by the CCFL for conservative first-principle estimate of the heatremovalcapability. From the maximum heatremoval point of view, the more the intra-debris pores and crevices, the greater the probability of the RPV survival than by the gap cooling mechanism alone.
Although no typical answer exists to explain the odd behavior of the Nanofluid material to date, researcher could properly explain the great privilege of the Nano particles over micro particles in formation of enriched fluid for their super-efficient heatremovalcapability. He et al. 2008 explains that on one hand micro/macro particle bring about little thermal enhancement to the base fluid while on the other hand abrasion, channel clogging and higher pressure drop are comparably higher than those of Nanofluids. Furthermore according to Eastman et al. 2004, to achieve such an enhancement concentrations above %10 of volume fraction must be applied which very readily face stability and rheological disorders. He et al. further highlights Nanofluids by their excellent stability, higher thermal conductivities than that predicted by currently available macroscopic models as well as their advantage of little pressure drop. Interestingly Eastman et al. has pointed out similar properties accompanying the advantages of strong temperature dependent effects and significant increase of critical heat flux (up to 3 times greater than the base fluid).
However, the conservatism and assumption of evaluation needs to be verified by using experimental data. In this study, an evaluation of LTCC capability for the APR1400 was performed using a RELAP5/MOD3.3 code. To simulate the core blockage in the RELAP5/MOD3.3 model, it was assumed that the pressure drops obtained from the in-vessel effect tests of the APR1400 occur at the core inlet during a hot-leg break or a cold-leg break of double ended guillotine. The effect of crud and chemical deposition were considered to evaluate the decay heatremovalcapability when LOCA-generated debris is deposited on a fuel cladding. In addition, full core blockage except one fuel assembly during a cold-leg break of double ended guillotine was simulated to investigate the limiting decay heatremovalcapability. RELAP5/MOD3.3 MODEL DESCRIPTION
pump was connected to the port provided in the compressor and the system was completely evacuated for the removal of any impurities before filling the refrigerants. This process was carried out for all the trials. Precision electronic balance with accuracy ±1% was used to charge into the system. Every time the system was allowed to stabilize for 10 min.
In flow measurement experiment, the focal point of this study is to determine the rate of contaminant removal for each cavity shapes with constant flow of water with high Reynolds numbers flow and the flow pattern within the cavity with low Reynolds number flow. The rate of contaminant removal was observed by a several aspect. The usage of Particle Imaging Technique provides the measurement of the whole flow field in qualitative manner. The present of contours of constant averaged stream wise and transverse components of velocity, contours of constant averaged vortices, Reynolds stress and streamline plots for each cavity type. In addition, stream wise velocity, Reynolds stress is compared for all cavity types. Effect of cavity shapes on flow structure within the cavity is discussed in details.
The FAM culturing method was applied to examine if any microorganism can pass alive through the 1% Ag-CA and the virgin membranes. All the test equipments and the membranes were sterilized before performing any trial. No living microorganism was found in the filtered water. This proves the membrane capability for complete removal of proposed species. The rejection test was performed for virgin and 1% Ag membranes. The latter was selected on the basis of highest permeability. Temperature (°C)
Abstract: This numerical study investigates the effect of using phase change material slurries (PCMs) on the thermal performance of micro channel used for cooling of high power electronic devices. The phase change material slurries composed of Lauric acid nanoparticles in water (carrier fluid) which is introduced into a rectangular micro channel of 100μm height and 10mm length, where bottom wall face a constant heat flux. Energy, momentum and mass equations are solved simultaneously using a carrier fluid with effective temperature dependent physical properties. Under specific conditions including mass flow rate of 1x10 -4 kg/s, heat flux of 0.7MW/m 2 and PCM nano-particles volume concentration (0-25%), results showed a remarkable
Abstract. This paper summarizes the basis for the solution of heatremoval by natural convection from both conventional nuclear reactors and reactors with fuel flowing coolant (such as reactors with molten fluoride salts MSR).The possibility of intensification of heatremoval through gas lift is focused on. It might be used in an MSR (Molten Salt Reactor) for cleaning the salt mixture of degassed fission products and therefore eliminating problems with iodine pitting. Heatremoval by natural convection and its intensification increases significantly the safety of nuclear reactors. Simultaneously the heatremoval also solves problems with lifetime of pumps in the primary circuit of high-temperature reactors.
In order to clarify the vulnerability of the Residual HeatRemoval (RHR) piping system for fragility analysis, a segment of the RHR piping that includes a heavy motor operated valve (MOV), flanged joint and reducer was numerically modelled to simulate the dynamic behaviour under strong earthquakes. Three kinds of tests were completed in this study to verify the accuracy of the numerical model. First, the pure bending tests with four-point cyclic loading were adopted for the flanged joint to investigate the nonlinear behaviours and establish reliable component models using finite element analysis software. Second, quasi-static tests for the chosen segments of piping were executed to carefully observe the response of the piping under cyclic loading. Finally, shaking table tests for the segment of RHR piping were completed to investigate its dynamic characteristics and to verify the numerical analysis results. According to the test results, the seismic performance of the RHR piping system in the sample nuclear power plant (NPP) is better than the assessment results in the Final Safety Analysis Report (FSAR). However, it’s noted that an unexpected failure mode of the flanged joint occurred during the pure bending test and caused the leakage of tested specimen.
Figure 3(a) represents variations in effectivity factor of heat exchanger in relation to the NTU in different temperatures of inlet cold water. As it can be seen in the figure, changes in water temperature do not affect the effectivity factor. But, increasing the NTU will give a rise to this factor. In order to show the effect of water flow rate entering the radiator, the thermal capacity which is 0.259 for DEZ radiators currently are used. Re- garding fixed flow rate of hot air versus changing flow rate of cold water around 30% to 40%, so there is no need to replace water pumps. The effect of the cold water flow rate fluctuation represented in Figure 3(b) in form of effectivity factor proportion to NTU at temperature of inlet water of 289 k for various thermal capacity rates of heat exchanger. By the way, it reveals that as the cooling water flow rate increase, it has a trivial rising effect on effectivity factor.
Ground source heat pump  is a highly efficient air conditioning system which takes advantage of shallow underground geothermal resource (also known as Ground Energy, including groundwater, soil or surface water) to provide both heat and cooling energy. It transfers heat energy from low temperature to high temperature by inputting a little amount of high-grade energy (e.g. electricity). In ground source heat pump systems, geothermal energy is used as the heating source of heat pumps in winter and the cooling source of air conditioning in summer. Ground source heat pump does not emit any exhaust gas, water and waste residues and thus is considered as an ideally green technology with renewable energy as well as a sustainable development technology. To trace its origin, it was first proposed and named as “Ground Source Heat Pump” by Zoelly from Swiss in 1912. As the name suggests, ground source heat pump is one type of heat pump, similar to air source heat pump. "Ground Source" is the low level heat of heat pump which is from ground. Ground source heat pump is classified into Ground-coupled heat pump (GCHP) and Water-source Heat Pump (WSHP) based on different ways of using low level heat.
As it has been seen in Figure 3, the percentage removal of both Mg and Ca metal from hard water is in- creased as the dose of cactus powder increased. The hard water (Mg) removalcapability of cactus powder is in- creased from 0.00% to 68.2% as the cactus powder increased from 0.0 g to 4.5 g. In the same way, the percen- tage removal of hard water (Ca) is increased from 0.00% to 79.2% as the dose of cactus powder increased from 0.0 g to 4.5 g. The slight decrement of percentage removal for both Ca and Mg metal beyond 2.5 g cactus powder might be due to the fact that re-dissociation of the trapped metal ions from hard water. The other proba- ble reason may be the exhausting of the active site of cactus powder that will need to be regenerated conti- nuously. Thus, in high adsorbent dose, the adsorption capacity is reduced due to overlapping of adsorption sites on adsorbent surface  .
capacity than the phase change garments, because the latent heat of water (around 2400 J/g) is at least 10 times greater than that of common phase change materials (around 150-250 J/. There have been several studies of wearable air ventilation vests for heat loss enhancement conducted on military personnel, law enforcement officers and firefighters working in hot environments (from 30℃ to more than 40℃). Strong airflows were required to insure that enough convective and evaporative heat loss occurred, but it was determined that the weight of the air ventilation vests, including the blower and all the necessary tubing systems, was too high (3.9kg [Chen 1997], 2.3kg [Xu 2011], 8kg [Chinevere 2008] and 1.2kg [Hadid 2008]). In our study, we are modeling a wearable air ventilation cooling system for office personnel in a moderately air- conditioned environment with temperatures around 27-30 ℃ . This system would be intended to expand the comfort range by only 3-6°C from the currently used range of 20-24°C, and is aimed at providing only moderate cooling. Thus, the airflow in our system could be weaker and the weight of the fans and batteries could be reduced to make it more amenable for regular personnel use.
The pragmatic nature of this research, which focused on understanding the realities of SMEs, called for an in-depth assessment of the model although the adjusted formative model satisfied statistical requirement after some items had been removed. The items which were removed carried the highest weights when the constructs were elicited qualitatively (Owoseni & Twinomurinzi, 2017). For example, “collaboration” and “package and prices adjustment of offering” weighted the highest as absorptive capability constructs of SMEs, but were removed in order to ensure reliability and validity of the measurement model. The removal could support the view that SMEs are highly heterogeneous entities (Derham & Cragg, 2011) which exposes their evasiveness when developing DCs homogeneously. Although SMEs “collaborate”, the ways in which they do so differ. This is also true of the adaptive capability where the “feedback and referrals” and “social media and internet usage” items were removed from the final structural model.
operation may be carried out using physical model. The experimental investigation reveals the concept of miniature heat pipes with noninverted meniscus with relations of main operation characteristic of evaporator. With the experimental test of MLHP with noninverted meniscus , Victar V. Maziuk  concluded that own thermal resistance of evaporator with noninverted meniscus is reduce as compare with thermal resistance of evaporators with inverted meniscus and additionally remove heat fluxes with much greater density. Le-lun JIANG  elaborate Miniature cylindrical metal powder sintered wick heat pipe is an ideal component with super-high thermal efficiency for high heat flux electronics cooling. The sintering process was optimally designed based on the equation of the heat transfer limit of sintered heat pipe The sintering parameters including with theory analysis through characterization of sintered wick, heat transfer limit of sintered heat pipe, optimization design of sintered wick and experimental steps like preparation, sintering process, sample testing. Result on the sintering temperature, sintering time, sintering atmosphere and sintering position were discussed. Viachaslau V. Doktarau, Victar V. Maziuk  focused on the concept of miniature loop heat pipe with noninverted meniscus with new principle and volume correlation for mLHP startup through experimental investigation. It experimental investigation of design and manufacture of mLHP with noninverted meniscus allow using capillary structure with high thermal conductivity, reduced in thermal resistance of evaporators. Also proved to remove heat fluxes with much greater density than mLHP with inverted meniscus. It studied more the concept of volume, porosity, compensation chamber, capillary structure in evaporation zone and vapour line for better
The artificial neural networks (ANNs) are strong tools for the prediction and simulation in various engineering applications. In this study, the heat transfer in an air cooled heat exchanger equipped with classic twisted tape inserts, is adopted as a function of two variables namely the twist ratio of classic inserts (Y) and Reynolds number (Re). Therefore an ANN model as shown in Figure2 is developed with the twist ratio (Y) ranging from 1.76 to 3.53 and Reynolds number (Re) from 4021 to 16118 as inputs and average Nusselt number (Nu) as desired output.
Hence, the utilization of low thermal conductivity building materials is important to decrease heat gain through the envelope into the building in hot climate country like Malaysia. Foamcrete has been acknowledged for its superior performance in thermal insulation and sound insulation characteristics due to its cellular microstructure. The thermal conductivity of foamcrete typically is 5 to 30% of that of normal weight concrete and range from between 0.1 and 0.7 W/mK for dry density values of 600 to 1600 kg/m 3 respectively [4,5]. In practical terms normal weight concrete would have to be 5 times thicker than foamcrete ones to achieve similar thermal insulation . The thermal conductivity of foamcrete with 1000 kg/m 3 density is reported to be one-sixth the value of typical cement-sand mortar . Since foamcrete is made by injecting air into a cement based mixture, the density of foamcrete is directly a function of the air inside foamcrete. Expectedly, the density of foamcrete should play an important role in determining its thermal properties. A reduction in foamcrete density by 100 kg/m 3 results in a lessening in its thermal conductivity by 0.04 W/mK .
Although the basic capability of AFM-based surface modification has been established, its wide-range of applicability as a viable nanomanufacturing technique has been hindered by several issues. First, the material removal mechanism is dominated by ploughing (i.e., plastic defor- mation) rather than shearing (i.e., removal of material in the form of a chip). This causes accumulation, rather than removal, of the material around the created features (i.e., ridge formation) [4, 6, 11]. Second, the throughput of the process is low due to the limited removal speeds, large force requirements, and associated rapid tool wear . Third, the depth of removal is dictated indirectly by pre- scribing the force by monitoring the deflection of the rel- atively low-stiffness AFM cantilever. Since the material removal force depends on factors such as material (surface) properties , probe geometry , and removal condi- tions (e.g., removal speed) , the resultant removal depth cannot be well-controlled through indirect prescrip- tion of depth using force monitoring. While several approaches have been proposed to address these issues, including the use of high-stiffness cantilevers , vibrating cantilevers [8, 12], and vibrating workpiece  or dia- mond tips (to reduce wear) , significant process improvements that will make tip-based mechanical mate- rial removal as a fully controllable nanomanufacturing technique have not yet been realized.