Latent Heat Of Condensation Research Articles

Development and eastward movement mechanisms of the Tibetan Plateau vortices moving off the Tibetan Plateau

Based on the Final operational global analysis data from the Global Forecasting System of the National Centers for Environment Prediction and the radiosonde data, the development and eastward movement mechanisms of 15 Tibetan Plateau vortices (TPVs) after they move off the plateau are investigated. The results show that the convergence to the east of the TPVs at 500 hPa, the divergence associated with the westerly jet stream at 200 hPa, as well as the corresponding ascending motion provide favorable conditions for the development and eastward movement of the TPVs. The spatial structures of the atmospheric apparent heat source (Q1) and the apparent moisture sink (Q2) are studied, showing that the heating centers of Q1 at 400 hPa mainly sourced from the condensation latent heat are beneficial to the eastward movement of the TPVs, while the horizontal distribution of Q1 at 500 hPa goes against that. The development and eastward movement mechanisms of the TPVs after they move off the plateau are further discussed through diagnosing the potential vorticity (PV) tendency equation. It is revealed that the horizontal PV flux convergence to the east of the TPVs related to the convergence at 500 hPa plays as the dominant role, exerting positive contribution to the PV tendency. Meanwhile, the heating fields induce feeble PV tendency, indicating more important effect of the dynamic factor. The development and eastward movement mechanisms of the TPVs after they move off the plateau are different from those before the TPVs move off, and the dynamic effect is vital in the former stage while the effect of Q1 is revealed as the dominant influencing factor in the latter.

Performance analysis of a thermoelectric generator applied to wet flue gas waste heat recovery

Thermoelectric generation technology, which is used to recover the waste heat of wet flue gas, is studied by establishing a mathematical model to analyze the generation characteristics of wet and dry flue gas. The effects of flue gas parameters are analyzed and discussed. The results show that differently from dry flue gas, when condensation occurs in wet flue gas, it not only releases a large amount of latent heat, but also increases the heat transfer coefficient between the flue gas and the module, and an increase in module area creates an inflection point in the output power curve for wet flue gas. Moreover, the maximum output power of wet flue gas is significantly larger than that of dry flue gas. The maximum output power and corresponding module area are clearly observed to increase as the gas flux increases, but the extreme value of generating efficiency decreases slightly. Specifically, as flue gas temperature increases, the maximum output power increases, whereas the optimal module area required remains unchanged beyond a certain temperature. In addition, an increase in the flue gas temperature has a greater impact on the performance of sensible heat. When the water vapor content decreases to a certain value, the maximum output power can be obtained without condensation. Therefore, there exists a critical water vapor content that can directly determine whether the latent heat of condensation can be recovered. This critical value increases as the flue gas temperature increases. Furthermore, increasing the flux ratio of cooling water and flue gas can also effectively reduce this critical value.

INCREASE OF ECOLOGICAL EFFECTIVENESS OF COMPLEX HEAT-RECOVERY SYSTEMS FOR BOILER PLANTS

It is revealed that the humidifying of blown air in complex heat recovery systems of gas-fired boiler plants provides the significant reduction in the concentration of nitrogen oxides in exhaust-gases due to the suppression of their formation in the boiler furnace when moisture is introduced with this air. 
 Problems of environmental protection and energy-saving became priority in world practice. The main directions of deciding these pressing problems in municipal heat-power engineering is to improve the environmental indicators of heating boiler plants and increase the efficiency of using fuel in them through the use of technologies for deep recovery of the exhaust-gases heat. The relevance of scientific problems in these directions is increasing due to the steady increase in the fuel-energy costs and the strengthening of requirements to reducing environmental pollution.
 When using these technologies of deep heat-recovery of exhaust-gases, the condensation mode of the heat-recovery equipment is realized, when, apart from to the so-called clear heat of these gases, the latent heat of condensation of the water vapor contained in them is also used. The condensation mode implementation also improves the ecological indicators of the boiler due to the reduction of fuel consumption and the dissolution in the resulting condensate of a part of harmful emissions formed during its combustion.
 The use of modern heat-recovery technologies for the gasfired boiler plants with complex use of recovered heat for the preheating of boiler water, water of the chemical waterpurification system and blowing air makes it possible to reduce fuel consumption in the boiler and, accordingly, its harmful emissions by 8...12 %.
 Humidification of the blowing air through the use of the recovery heat also provides a reduction of nitrogen oxides emissions to 60 % by suppressing their formation in the boiler combustion chamber.

Migration of contact binary cyclones and atmospheric river: Case of explosive extratropical cyclones in East Asia on December 16, 2014

Contact binary cyclones have been observed often in the marginal sea areas of East Asia; however, their explosive development and related moisture transport are not understood fully. This study investigated explosive extratropical binary cyclones that occurred near Japan on December 16, 2014, to elucidate both their explosive development and their efficient transport of moisture northward. The northernmost of the binary cyclones developed with a central pressure fall of 24 hPa during a 24-h period. It remained over the Japan Sea, where a trough and an area of high potential vorticity were located at 300 hPa. The southernmost of the binary cyclones developed explosively with a central pressure fall of 58 hPa during a 24-h period. It traveled rapidly around the northern low in a counterclockwise direction. The contact binary cyclones accompanied a tributary atmospheric river and moist delta, which aided the rapid development of the southern low. The tributary atmospheric river was formed by the regional convergence of humid air parcels that were modified by the surface moisture flux around the cold front (though the atmospheric river was extended from the tropical Pacific Ocean). As the southern low developed, northward moisture transport was predominant along the atmospheric river. In the explosive binary cyclones, the influence of latent heat release differed between the two contact lows. While the northern low was coupled with the upper-level trough over the Japan Sea, the southern surface low, which revolved around the northern low, was intensified both by the latent heat release and by the warm horizontal thermal advection and the vorticity advection along a front. Condensational latent heating did not influence substantially the pressure drop of the northern low, whereas it contributed considerably to the formation of the southern low and to the enhancement of the northward moisture transport along the atmospheric river.

Desalination of Seawater by Liquid Columns and Decompression Boiling (Recovery of Condensation Latent Heat)

In this study, the concept of a new seawater desalination method and equipment using liquid columns of seawater and desalinated fresh water, decompression boiling and evaporation, condensation, and recovery of condensation latent heat are proposed. The equipment consists of seawater and freshwater columns approximately 10 m high with top spaces. The pressure of the top space, the evaporation and condensation area, of the seawater column, for example, is reduced approximately 30 mmHg (abs.) using the seawater column, after which it is heated from the general seawater temperature of 25°C to 30°C to boil and evaporate the seawater. The vapor is cooled by the seawater at approximately 25°C in a heat exchanger, and then, it is condensed and sent to the fresh water column. At this time, the condensation latent heat is recovered to preheat the newly flowing seawater. The evaporation or condensation rate, namely, the production rate of freshwater, by the new desalination equipment is also estimated by the results of the existing quadruplex effect vacuum evaporator used in the salt production industry. This new desalination method and its associated equipment also can be used to purify polluted water and waste water.

Possible Effect of the Thermal Condition of the Tibetan Plateau on the Interannual Variability of the Summer Asian–Pacific Oscillation

The summer (June–August) Asian–Pacific Oscillation (APO), a large-scale atmospheric teleconnection pattern, is closely associated with climate anomalies over the Northern Hemisphere. Using the NOAA/CIRES twentieth-century reanalysis, the ECMWF twentieth-century atmospheric reanalysis, and the NCEP reanalysis, this study investigates the variability of the summer APO on the interannual time scale and its relationship with the thermal condition over the Tibetan Plateau (TP). The results show that the interannual variability of the APO is steadily related to the summer TP surface air temperature during the last 100 years. Observation and simulation further show that a positive heating anomaly over the TP can increase the upper-tropospheric temperature and upward motion over Asia. This anomalous upward flow moves northward in the upper troposphere, and then turns and moves eastward, before finally descending over the mid- to high latitudes of the central-eastern North Pacific, concurrently accompanied by anomalous upward motion over the lower latitudes of the central-eastern North Pacific. The anomalous downward and upward motions over the central-eastern North Pacific reduce the in situ mid- and upper-tropospheric temperature, mainly through modulating condensation latent heat from precipitation and/or dry adiabatic heat, which ultimately leads to the interannual variability of the summer APO. In this process, the zonal vertical circulation over the extratropical Asian–North Pacific sector plays an important bridging role.

LIFE CYCLE COSTING AND PAYBACK PERIOD EVALUATION OF A SOLAR THERMAL DESALINATION SYSTEM

Water is important for life and development. About 1.8 billion people will be living in absolute water scarcity by 2025.Non availability of safe drinkable water is the major source of diseases in the different regions of the world especially remote rural and coastal areas. About 97% of water on earth is comprised of seawater. Desalination of saline water is a prominent approach to handle the problem of water scarcity. Conventional desalination technologies cause economic and environmental problems due to their dependency upon fossil fuels. Solar flash desalination is one of the best desalination techniques in the developing stages. Solar energy, passive vacuum and recovery of latent heat of condensation make this system a sustainable option for desalination. In this paper, economic analysis of the solar thermal desalination system of saline water is presented. The unit cost of desalinated water is found to be US$ 0.0147 per litre. The energy and emission payback (EEP) period for vacuum chamber and solar collector has also been presented. The energy payback period of solar collector and vacuum chamber are found to be 1.3 years and 1.5 years respectively. The emission payback period of solar collector and vacuum chamber are found to be 1.8 years and 2.1 years respectively.

Analysis of thermoelectric generation characteristics of flue gas waste heat from natural gas boiler

For the large quantity of water vapor present in the exhaust gas of natural gas boilers, the waste heat of the flue gas is not only determined by the sensible heat, but also by the latent heat of condensation. In this study, a generation model was established in order to investigate the thermoelectric generation characteristics of the wasted flue gas heat. The calculated results show that the characteristics curves can be divided into a sensible heat generation region and a mixed power generation region, with the power generation performance of both regions having different characteristics. Considering that the heat transfer coefficient of wet flue gas is higher than that of dry flue gas, this paper proposes to improve the performance of the generator through gas humidification, which not only improves the maximum output power, but also reduces the area of the thermoelectric module required for maximum power output. In addition, a thermoelectric power generation system created by intermediate humidification of flue gas, and which can fully utilize high-temperature flue gas and improves the power performance of thermoelectric generators at a lower temperature is presented. An optimum intermediate humidification temperature that results in maximum output power at the smallest corresponding module area is also determined.

Characteristics of static pre-cyclonic steam ejector

The thermal vapor recompression (TVR) technology can partially recover condensation latent heat of the secondary steam in the multi-effect evaporation (MEE) process. And the two-dimension of x and r momentum exchange in the key device-steam ejector, makes induction efficiency relatively low and mixing length long. In this article, a novel three-dimensional momentum exchanging ejector called static pre-cyclonic steam ejector (SCSE) is first proposed. Its performances are mainly evaluated by means of computational fluid dynamics(CFD) at different dynamic pressure ratios (DPRs) and preliminarily validated by experiments. The SCSE can not only reduce the axial dimension of conventional ejector, but also show excellent performance at a low boosted pressure occasions. The SCSE with DPR = 4/1 improves the entrainment ratio(ER) by 10.8% compared to traditional ejector. For cases with secondary flow pressure disturbances, the application of the SCSE is limited because of an adverse impact on the operation stability. For cases with outlet flow fluctuates, the SCSE with larger DPR has higher peak ER and narrower choked-band-width at respective break-down supercharging ratios (BSRs), and there are no obvious influences on the operation stability for SCSE.

Effect of the atmospheric quasi-biweekly oscillation on the vortices moving off the Tibetan Plateau

In the present study, the relationship between the atmospheric quasi-biweekly oscillation (QBWO) and Tibetan Plateau vortices (TPVs) moving off the Tibetan Plateau was investigated based on the radiosonde and reanalysis data. It is found that the number of TPVs moving off the Tibetan Plateau (moving-off TPVs) has the distinct feature of the 10–20-day QBWO. 77% of the moving-off TPVs occur in the positive phases of the 10–20-day filtered 500 hPa vorticity over eastern Tibetan Plateau. Besides, distributions of the zonal and meridional components of E-vectors coincide well with the trajectories of TPVs, indicating the moving-off TPVs are well related with the propagation of the QBWO energy. The atmospheric circulations and related thermodynamic fields are discussed to reveal the mechanism of the effect of 10–20-day QBWO on the moving-off TPVs. It is found that the atmospheric circulations and heating fields of 10–20-day QBWO have major impact on the moving-off TPVs. In positive QBWO phases, at 500 hPa over eastern Tibetan Plateau, there appear negative geopotential height anomalies and anomalous cyclonic wind shear; the anomalous jet stream and positive geopotential heights at 200 hPa lying over the northeast of the Tibetan Plateau stretch eastward gradually, benefiting for the upper level divergence and ascending motion. The condensation latent heat is released and shifts eastward with the heating centers located at 400 hPa, which depresses the isobaric surface at 500 hPa. All these conditions are in favor of the maintenance and eastward movement of TPVs in the positive QBWO phases.

Effects of Latent Heating on Atmospheres of Brown Dwarfs and Directly Imaged Planets

Abstract The growing number of observations of brown dwarfs (BDs) has provided evidence for strong atmospheric circulation on these objects. Directly imaged planets share similar observations and can be viewed as low-gravity versions of BDs. Vigorous condensate cycles of chemical species in their atmospheres are inferred by observations and theoretical studies, and latent heating associated with condensation is expected to be important in shaping atmospheric circulation and influencing cloud patchiness. We present a qualitative description of the mechanisms by which condensational latent heating influences circulation, and then illustrate them using an idealized general circulation model that includes a condensation cycle of silicates with latent heating and molecular weight effect due to the rainout of the condensate. Simulations with conditions appropriate for typical T dwarfs exhibit the development of localized storms and east–west jets. The storms are spatially inhomogeneous, evolving on a timescale of hours to days and extending vertically from the condensation level to the tropopause. The fractional area of the BD covered by active storms is small. Based on a simple analytic model, we quantitatively explain the area fraction of moist plumes and show its dependence on the radiative timescale and convective available potential energy (CAPE). We predict that if latent heating dominates cloud formation processes, the fractional coverage area of clouds decreases as the spectral type goes through the L/T transition from high to lower effective temperature. This is a natural consequence of the variation of the radiative timescale and CAPE with the spectral type.

A deforestation-induced tipping point for the South American monsoon system

The Amazon rainforest has been proposed as a tipping element of the earth system, with the possibility of a dieback of the entire ecosystem due to deforestation only of parts of the rainforest. Possible physical mechanisms behind such a transition are still subject to ongoing debates. Here, we use a specifically designed model to analyse the nonlinear couplings between the Amazon rainforest and the atmospheric moisture transport from the Atlantic to the South American continent. These couplings are associated with a westward cascade of precipitation and evapotranspiration across the Amazon. We investigate impacts of deforestation on the South American monsoonal circulation with particular focus on a previously neglected positive feedback related to condensational latent heating over the rainforest, which strongly enhances atmospheric moisture inflow from the Atlantic. Our results indicate the existence of a tipping point. In our model setup, crossing the tipping point causes precipitation reductions of up to 40% in non-deforested parts of the western Amazon and regions further downstream. The responsible mechanism is the breakdown of the aforementioned feedback, which occurs when deforestation reduces transpiration to a point where the available atmospheric moisture does not suffice anymore to release the latent heat needed to maintain the feedback.

Diagnosis of the forcing of inertial-gravity waves in a severe convection system

The non-hydrostatic wave equation set in Cartesian coordinates is rearranged to gain insight into wave generation in a mesoscale severe convection system. The wave equation is characterized by a wave operator on the lhs, and forcing involving three terms—linear and nonlinear terms, and diabatic heating—on the rhs. The equation was applied to a case of severe convection that occurred in East China. The calculation with simulation data showed that the diabatic forcing and linear and nonlinear forcing presented large magnitude at different altitudes in the severe convection region. Further analysis revealed the diabatic forcing due to condensational latent heating had an important influence on the generation of gravity waves in the middle and lower levels. The linear forcing resulting from the Laplacian of potential-temperature linear forcing was dominant in the middle and upper levels. The nonlinear forcing was determined by the Laplacian of potential-temperature nonlinear forcing. Therefore, the forcing of gravity waves was closely associated with the thermodynamic processes in the severe convection case. The reason may be that, besides the vertical component of pressure gradient force, the vertical oscillation of atmospheric particles was dominated by the buoyancy for inertial gravity waves. The latent heating and potential-temperature linear and nonlinear forcing played an important role in the buoyancy tendency. Consequently, these thermodynamic elements influenced the evolution of inertial-gravity waves.

Mathematical Modeling of Dual Layer Shell Type Recuperation System for Biogas Dehumidification

Abstract The main aim of the current paper is to create a mathematical model for dual layer shell type recuperation system, which allows reducing the heat losses from the biomass digester and water amount in the biogas without any additional mechanical or chemical components. The idea of this system is to reduce the temperature of the outflowing gas by creating two-layered counter-flow heat exchanger around the walls of biogas digester, thus increasing a thermal resistance and the gas temperature, resulting in a condensation on a colder surface. Complex mathematical model, including surface condensation, is developed for this type of biogas dehumidifier and the parameter study is carried out for a wide range of parameters. The model is reduced to 1D case to make numerical calculations faster. It is shown that latent heat of condensation is very important for the total heat balance and the condensation rate is highly dependent on insulation between layers and outside temperature. Modelling results allow finding optimal geometrical parameters for the known gas flow and predicting the condensation rate for different system setups and seasons.

Review of solar, heat pipe and thermoelectric hybrid systems for power generation and heating

Abstract Solar energy is a renewable energy heat source freely and widely available everywhere throughout the year.Heat pipes are veryeffective and passive heat transfer devices. A solar heat pipe collector performs well at hightemperatures. Thermoelectricity could be utilized for power generation and provide cooling and heating. Thecombination of a solar heat pipe collector with thermoelectric modules could provide a very useful device forsimultaneous power generation and hot water heating. Such hybrid systems could offer small, mobile,transportable and off-grid power and heating systems for small-scale industry or domestic applications. Thispaper reviews some of theworks conductedon the solar/heat pipe/thermoelectric hybridsystem. Keywords: solar; heat pipe; thermoelectric; power generation; water heating Received 20 November 2014; revised 10 June 2015; accepted 22 July 2015 1 INTRODUCTION Solar energy is a renewable energy heat source freely and widelyavailable everywhere worldwide and throughout the year. Solarapplications can be classified under the headings of solar thermalor solar photovoltaic (PV). Numerous texts are available on thesubjectofsolarenergy[1,2].Heat pipes (HPs) are very effective and passive heat transferdevices that are capable of transferring large amounts of heatthrough long distances with small temperature differencesbetween the heat source and the heat sink. A HP consists of asealed copper pipe, vacuumed and filled with acertain amount ofworking fluid. There are three distinct sections in the pipe. Theevaporator section is separated from the condenser section by ashort adiabatic section. Heat applied over the evaporator sectionof the pipe causes the fluid to boil internally and vaporize,picking up latent heat of vaporization. The vapor travels insidethe sealed pipe to the condenser section where it condenses,giving up its latent heat of condensation. The condensate is thentransported back to the evaporator section either by gravityor viainternally incorporated wicks. Heat is thus transferred from theevaporator to the condenser section of the pipe. ComprehensiveoverviewsofHPscanbefoundinReferences[3–6].Thermoelectric (TE) is the direct conversion of a tempera-ture difference imposed between the junctions of twodissimilar materials to electricity. This is known as the Seebeckeffect and attributed to Thomas Seebeck in the nineteenthcentury.ItsapplicationissometimesreferredtoasTEpowergeneration (TEG). Later, Peltier showed that the converse istrue. By imposing avoltage across or passing a current throughtwo dissimilar materials, a temperature gradient is createdbetween them. A hot surface in contact with the cold junctionoftheTEwillbecooleddownandvice versa, a cold surfacein contact with the hot junction will be heated up. This effectcan be used for TE cooler (TEC) heat pump heating andcooling applications. Some useful references could be found inReferences [7,8].A typical solar/HP/TE (SHPTE) hybrid system consists of asolar HP collector with a TE module connected at the condenserend as illustrated in Figure 1a. The TE module is cooled with awater-cooled jacket or by an air-cooled fin heat sink. In order toobtain high temperatures, the solar collector is normally of theevacuated tube HP solar collector (ETHPSC) type. An end viewof a typical ETHPSC unit is shown in Figure 1b. The glass enve-lope consists of two concentric glass tubes with a selective surfacecoating applied on the outer surface of the inner tube. The tubesare evacuated and sealed at the ends. This reduces heat loss to theambient and results in a high-performance unit. A smaller diam-eter copper HP is suspended in the center of the evacuated glasstubes and held in place by a pre-formed aluminum fin wrapped

Condensation of water vapor and carbon dioxide in the jet exhausts of rocket engines: 1. Heterogeneous condensation of combustion products

Condensation of water vapor and carbon dioxide in the jet exhausts of rocket engines during last stages of Proton, Molniya, and Start launchers operating in the upper atmospheric with different types of fuels is considered. Particle heating is taken into account with emission of latent heat of condensation and energy loss due to radiation and heat exchange with combustion products. Using the solution of the heat balance and condensed particle mass equations, the temporal change in the temperature and thickness of the condensate layer is obtained. Practically, no condensation of water vapor and carbon dioxide in the jet exhaust of a Start launcher occurs. In plumes of Proton and Molniya launchers, the condensation of water vapor and carbon dioxide can start at distances of 120–170 m and 450–650 m from the engine nozzle, respectively. In the course of condensation, the thickness of the “water” layer on particles can exceed 100 A, and the thickness of carbon dioxide can exceed 60 A.

A comparison of summer precipitation structures over the South China Sea and the East China Sea based on tropical rainfall measurement mission

The three-dimensional structures of summer precipitation over the South China Sea (SCS) and the East China Sea (ECS) are investigated based on tropical rainfall measurement mission (TRMM). The primary results are as follows. First, both the convective and stratiform precipitation rates in the SCS are much higher than those of the ECS. The contribution of the convective cloud precipitation to the surface precipitation is primarily over the SCS and the ECS with a proportion of about 70%, but the contribution of convective cloud precipitation is slightly larger in the SCS than the ECS. The contribution of stratus precipitation is slightly larger in the ECS than that in the SCS. Second, the content of cloud particles and precipitation particles in the ECS in June was greater than that in the SCS, while in July and August, the content of cloud and precipitation particles in the ECS was less than that in the SCS. Third, the latent heat profile of the ECS is quite different from that of the SCS. In June, the peak values of evaporation and condensation latent heating rates in the ECS are greater than those in the SCS. In July and August, however, the peak values of evaporation and condensation latent heating rates in the ECS are about 0.05°/h less than those in the SCS.

Homogeneous Condensation in Supersonic Impinging Jets onto Cylindrical Cavity

Over half a century researchers have engaged themselves in doing research on supersonic impinging jets for their fundamental fluid dynamic perspectives as well as their huge practical applications. In a variety of engineering applications steam or moist air is used as working gas. Rapid expansion of steam or moist air leads to an occurrence of non-equilibrium homogeneous condensation at the region between downstream of nozzle exit and an obstacle. Surrounding gas is heated due to the release of latent heat of condensation, and may affect the jet flow features. The present numerical work deals with the effect of condensation on the aerodynamic and oscillatory flow features of supersonic impinging jets onto a cylindrical cavity. A TVD scheme is used to solve the RANS equations and droplet growth equations for simulating condensation in the jet flowfield. The numerical code is validated through comparison with experimental results. Predicted flow and oscillatory properties of jets are presented.

Aerosol Effects on Simulated Storm Electrification and Precipitation in a Two-Moment Bulk Microphysics Model

Abstract The effects of cloud condensation nuclei (CCN) concentrations are found to strongly affect the microphysical and electrical evolution of a numerically simulated small multicell storm. The simulations reproduce the well-known effects of updraft invigoration and delay of precipitation formation as increasing CCN from low to intermediate concentrations causes droplet sizes to decrease. Peak updrafts increased from 16 m s−1 at the lowest CCN to a maximum of 21–22 m s−1 at moderate CCN, where condensation latent heating is maximized. The transition from low to high CCN first maximizes warm-rain production before switching over to the ice process as the dominant precipitation mechanism. Average graupel density stays fairly high and constant at lower CCN, but then drops monotonically at higher CCN concentration, although high CCN also foster the appearance of small regions of larger, high-density graupel with high simulated radar reflectivity. Graupel production increases monotonically as CCN concentration rises from 50 to about 2000 cm−3. The lightning response is relatively weak until the Hallett–Mossop rime-splintering ice multiplication becomes more active at CCN > 700 cm−3. At very high CCN concentrations (>2000 cm−3), graupel production decreases slowly, but lightning activity drops dramatically when the parameterization of Hallett–Mossop rime-splintering ice multiplication is based on the number of large cloud droplets collected by graupel. Conversely, lightning activity remains steady at extremely high CCN concentration when the Hallett–Mossop parameterization is based simply on the rate of rime mass accumulation. The results lend support to the aerosol hypothesis as applied to lightning production, whereby greater CCN concentration tends to lead to greater lightning activity, but with a large sensitivity to ice multiplication.

NUMERICAL ANALYSIS OF IDEALLY-EXPANDED SUPERSONIC JETS WITH NONEQUILIBRIUM HOMOGENEOUS CONDENSATION

Steam or moist air is used as working gas in a wide range of engineering applications of supersonic jets. In these cases, nonequilibrium homogeneous condensation may occur at the downstream of nozzle throat. The surrounding gas will be heated by the release of latent heat of condensation, and may results a change in the flowfield. The present report will describe numerical investigations predicting the effect of nonequilibrium condensation on the flow characteristics of ideally-expanded supersonic free jets. A TVD numerical method is applied to solve RANS and droplet growth equations. The predicted results are compared with the experimental data.