Reduced Heat Transfer Research Articles

Integral effect test for steam line break with coupling reactor coolant system and containment using ATLAS-CUBE facility

To improve safety analysis technology for a nuclear reactor containment considering an interaction between a reactor coolant system (RCS) and containment, this study aims at an experimental investigation on the integrated simulation of the RCS and containment, with an integral effect test facility, ATLAS-CUBE. For a realistic simulation of a pressure and temperature (P/T) transient, the containment simulation vessel was designed to preserve a volumetric scale equivalently to the RCS volume scale of ATLAS. Three test cases for a steam line break (SLB) transient were conducted with variation of the initial condition of the passive heat sink or the steam flow direction. The test results indicated a stratified behavior of the steam-gas mixture in the containment following a high-temperature steam injection in prior to the spray injection. The test case with a reduced heat transfer on the passive heat sink showed a faster increase of the P/T inside the containment. The effect of the steam flow direction was also investigated with respect to a multi-dimensional distribution of the local heat transfer on the passive heat sink. The integral effect test data obtained in this study will contribute to validating the evaluation methodology for mass and energy (M/E) and P/T transient of the containment.

New functional materials for creating infrastructure facilities in the Arctic and Far North regions

The article presents aspects of the production of new functional building materials based on foam glass, reproducing the geological processes of formation of natural minerals and rocks. The creation of heat-insulating and structural glass composites (TCS) with increased strength requires the development of a new theoretical base that allows one to design various composites with an amorphous-crystal structure, which forms the specified properties. Two methods of amorphous matrix reinforcement are considered: physical and chemical (or thermochemical). Regularities of formation of porous glass composites are established. The values of technological parameters that are necessary for obtaining glass composites with the specified properties are determined. It is shown that the developed materials can be used for the construction of unique structures with reduced heat transfer. The resulting materials can be used to produce light prefabricated segments, which is important for transportation and installation in the Northern regions.

Thermal insulators based on abundant waste materials

Any airconditioned zone must be thermally insulated from its surroundings to maintain the desired temperature. Thermal insulators thus play a significant role in reducing heat transfer between airconditioned areas and their surroundings to save energy. Thermal insulators are usually made from materials with low thermal conductivity, and to reduce the cost of such insulators, this study investigated the use of waste organic materials as thermal insulators. This study is the second part of a project that aims to achieve an optimised insulator from both the thermal and economic perspectives. To achieve this, the heat conductivity of five different samples made from hair, grass, date seed, and date palm fibre were examined. The all samples were made with industrial white glue as a binder. The heat flow method was employed to determine their thermal conductivity, with results that showed that all samples offered thermal resistance to heat transfer in the range 0.0530 to 0.1068 W/mK. The best thermal resistance was provided by the sample made from hair and fibres. The current study supports sustainability by encouraging the use of waste organic materials in thermal insulators.

Retrospective analysis of a multi-stage experiment on developing high-performance insulation panels to sustain jet impingement at high temperatures

Over the years, numerous insulation panels have been developed to reduce heat transfer and meet the growing requirements imposed by industries. For a panel, the topology of the core can be delicately designed while novel and advanced materials are put into use. However, in the shipbuilding industry, the development of high-performance insulation panels using low-cost or cost-effective materials is still in great demand. A four-stage experimental study was conducted to develop high-temperature-proof panels without major thermal bridges caused by fastening methods for ships. A specimen chamber matching setup was used to test 36 panels based on nine designs with three commonly found core materials, i.e., polycrystalline filaments (PF), silica aerogel (SA), and aluminum silicate, under an impinging jet at temperatures ranging from 500 to 585 °C for 30 min. Besides analyzing overall heat transfer coefficient (U), heat flux (q), and Fourier number (Fo) for all panels, a method was proposed to estimate thermal diffusivity at testing temperatures (α) based on the Levenberg–Marquardt algorithm and an analytical model of heat conduction. Major conclusions include the following: First, thermal properties varied among the eligible panels: U: 0.4–1.43 W·m−2·°C−1; q: 100–318 W/m2; α: 6.0 × 10–8–1.3 × 10–6 m2/s; and Fo: 0.07–0.35. Second, because the improvement of thermal performance by adding an air interlayer was not significant, traditional panel designs with internal insulation were preferable. Third, by balancing thermal performance and economic and practical considerations, panels with SA or PF core and fastened by in-core battens were recommended for large-scale industrial applications, and it would be more cost-effective to use PF core.

A comprehensive experimental investigation of low-temperature combustion with thick thermal barrier coatings

Thick thermal barrier coatings (TBCs) have a significant potential to increase thermal efficiency by reducing heat transfer losses. However, in conventional combustion modes, the drawbacks associated with charge heating and higher propensity to knock have outweighed the efficiency benefits. Since the advanced low-temperature combustion (LTC) concepts are fundamentally different from the conventional combustion modes, these penalties do not exist in most of LTCs.The current experimental study shows the feasibility and benefits of thick TBCs with advanced LTC enabled by two different fuels: conventional gasoline and wet ethanol 80 (WE80, i.e., 80% ethanol and 20% water by mass). A total of five pistons were tested, including two metal baselines and three TBC-coated pistons with different thicknesses or surface finishes. A load sweep was conducted with each fuel on each piston within the same constraints. The thick TBCs extends the low load limit by about 15% for both gasoline and WE80 cases. A deterioration of the high load limit was not observed, which implies that the charge heating penalty does not occur in LTCs. The combustion efficiency increased for the thicker TBC by up to 2% points, and the fuel conversion efficiency was increased by up to 4.3%. The gasoline cases experience the largest benefits at low load, while the wet ethanol experiences the largest benefits at mid-to-high load. The intake temperature requirement is successfully reduced by 10–15 K. It is also observed that the dense sealing layer results in a significant improvement to UHC emissions. All of the coated pistons survived the 10–20 h of engine operation with no visual failure.

Research of Curing Time and Temperature-Dependent Strengths and Fire Resistance of Geopolymer Foam Coated on an Aluminum Plate

Geopolymer foam (GF) uses a potassium activator and can be cured at high temperatures, which can improve its mechanical properties. In this study, we attempted to test this hypothesis by comparing the flexural and compressive strength, apparent density and fire resistance of GF. The composition of the GF used in the experiment included a potassium activator, basalt ground fiber and aluminum powder with a mass ratio to the binder of 0.45, 0.3 and 0.015, respectively. The samples were cured at room temperature and at 50, 70, 85 and 105 °C with a curing time of 2, 4, 6, 12 and 24 h. Then, the samples were kept until being tested on the third, seventh, 14th and 28th day. The results showed that the flexural and compressive strength and apparent density improved and stabilized after seven days at 85 °C. Furthermore, the GF exhibited a substantial increase after three days in its flexural strength by 111% and compressive strength by 122.9% at the optimal temperature of 85 °C for 2 h compared to the values at RT after 28 days. The GF had an apparent density of 0.558–0.623 g/cm3 on the 28th day. As a new alternative to aluminum materials, investigating the fire resistance of sandwich panels (an aluminum plate covered with a GF layer) is important for their safe impregnation. Sandwich panels with thicknesses of 10–20 mm were exposed to a gas fire. The test results showed that the sandwich panels had significantly improved fire resistance compared to unprotected panels. The longest fire resistance times for the aluminum plate coated with 20 mm of GF layer thickness was 7500 s. Thus, the GF coated on the aluminum plate exhibited superior fire resistance and a reduced heat transfer rate compared to uncoated panels.

Evaluation of pressure reconstruction techniques for Model Order Reduction in incompressible convective heat transfer

This paper compares pressure reconstruction strategies in Model Order Reduction for incompressible flows with convective heat transfer. The Navier-Stokes equation are reduced along with the passive scalar transport equation for the temperature using the POD-Galerkin technique. Six different pressure reconstruction methods are evaluated, two of which are novel to the best of the authors’ knowledge. Accurate pressure reconstruction is key to avoid error buildup in when solving for the conservation of linear momentum at the reduced level. The six approaches are compared using Direct Numerical Simulations of convective heat exchange processes in a 3D Backward Facing Step with a heated cylinder. When comparing time-averaged metrics, we observe that the reconstruction methods that approximate the reduced pressure field using techniques borrowed from full order models (mechanical analogy, pressure Poisson, and velocity supremizers) yield higher errors than the methods that seek to stabilize the reduced systems (reduced residual stabilization, artificial divergence, and Uzawa operator).

Minimization of Entropy Generation Rate in Hydrogen Iodide Decomposition Reactor Heated by High-Temperature Helium.

The thermochemical sulfur-iodine cycle is a potential method for hydrogen production, and the hydrogen iodide (HI) decomposition is the key step to determine the efficiency of hydrogen production in the cycle. To further reduce the irreversibility of various transmission processes in the HI decomposition reaction, a one-dimensional plug flow model of HI decomposition tubular reactor is established, and performance optimization with entropy generate rate minimization (EGRM) in the decomposition reaction system as an optimization goal based on finite-time thermodynamics is carried out. The reference reactor is heated counter-currently by high-temperature helium gas, the optimal reactor and the modified reactor are designed based on the reference reactor design parameters. With the EGRM as the optimization goal, the optimal control method is used to solve the optimal configuration of the reactor under the condition that both the reactant inlet state and hydrogen production rate are fixed, and the optimal value of total EGR in the reactor is reduced by 13.3% compared with the reference value. The reference reactor is improved on the basis of the total EGR in the optimal reactor, two modified reactors with increased length are designed under the condition of changing the helium inlet state. The total EGR of the two modified reactors are the same as that of the optimal reactor, which are realized by decreasing the helium inlet temperature and helium inlet flow rate, respectively. The results show that the EGR of heat transfer accounts for a large proportion, and the decrease of total EGR is mainly caused by reducing heat transfer irreversibility. The local total EGR of the optimal reactor distribution is more uniform, which approximately confirms the principle of equipartition of entropy production. The EGR distributions of the modified reactors are similar to that of the reference reactor, but the reactor length increases significantly, bringing a relatively large pressure drop. The research results have certain guiding significance to the optimum design of HI decomposition reactors.

Effect of three structurally different epoxy resins on fire resistance, optical transparency, and physicomechanical properties of intumescent fire-retardant transparent coatings

Transparent intumescent fire-retardant (IFR) coatings are the newest passive fireproofing materials which maintain structural integrity without losing aesthetic appearance of the substrate. In this present paper, effects of three IFR coatings with structurally different epoxy resins, namely aliphatic, cycloaliphatic, and aromatic, on the fire resistance, transparency, and physicomechanical properties were investigated. Different phosphate resin acids (PRA) were prepared by reacting synthesized phosphate ester acid (PEA) with aliphatic, cycloaliphatic, and aromatic epoxy resins. The chemical structures of the above PEA and PRAs were confirmed by Fourier transform infrared spectroscopy (FTIR), 1H-nuclear magnetic resonance spectroscopy (1H-NMR), and 31P-nuclear magnetic resonance spectroscopy (31P-NMR). Subsequently, transparent IFR coatings were prepared by mixing these PRAs with hexamethoxy methyl melamine resin. Transparency of the coatings was confirmed by UV–Vis–NIR spectrophotometeric studies. Fire protection property and char compressive strength were done to investigate the fire protection ability of the coatings, and the quality of the char formed was analyzed by field emission scanning electron microscope. The decomposition process of prepared fire-retardant coatings was studied by thermogravimetric analysis. Results showed that aliphatic epoxy-based transparent coating produced tough and compact char, but the char height was negligible, and aromatic epoxy-based transparent coating produced soft and fluffy char having excellent char height; however, the fluffy char reduced protection for longer duration. Cycloaliphatic epoxy-based transparent coating produced tough and compact char with good char height, thereby reducing heat transfer during combustion, and also showed superior scratch, abrasion, impact, and water resistance compared to other compositions.

Thermodynamic and experimental analysis of turbocharger for a downsized LPG fuelled automotive SI engine

There has been extensive research on efficient energy conversion systems which also includes turbocharging the automotive SI engine. This research focuses on comparing the thermodynamic aspects of the turbine at different boost pressures at maximum engine torque and speed regions. A naturally aspirated CNG SI engine developing 15.5 kW at 3400 rpm was converted to a turbocharged LPG engine at the compression ratio of 8.5:1. The turbine performance was evaluated using ANSYS CFX numerical simulation tool and results were validated. The simulation study reveals that 1.3 bar boost pressure has a higher enthalpy generation and also has minimal Mach number than 1.5 bar signifying the effects of exhaust blowdown. Further, the experimental study was carried out at different boost pressures. The results show that at 1.3 bar, the turbine efficiency was higher with reduced heat transfer rate to the compressor which was due to reduced friction work compared to 1.5 bar which altogether improved the engine performance. This is also evident from the minimal COV of IMEP for 1.3 bar. On the whole, the turbine exhibited better performance for 1.3 bar and resulted in reduced thermal loading.

Theoretical Minimum Thermal Load in Buildings

Summary Building cooling and heating accounts for a large portion of total global energy use and requires commensurate amounts of resources, which contribute significantly to global warming. Traditionally, addressing this issue has meant improving the efficiency of equipment supplying the thermal energy, reducing envelope heat transfer, and reducing air infiltration. However, this approach is already reaching practical limits. In this perspective, we explore (1) how to reduce thermal load in buildings theoretically and (2) how to achieve that reduction and dramatically lower the energy required to support building loads practically. First, we discuss our framework developed for calculating the theoretical minimum thermal load (TMTL) in buildings. Our analysis shows that current thermal loads in buildings are more than an order of magnitude higher than the TMTL. We also introduce an approximate formula to calculate energy savings from zonal control of thermal load, which shows that the majority of zonal control benefits can be achieved with fewer than 10 zones. Then, we discuss pros and cons of various approaches and strategies to achieve the TMTL. We conclude our perspective with some longer-term R&D ideas, such as thermally adaptive clothing and thermal storage to help approach the TMTL, while providing the additional benefit of interacting with the renewable grid of the future.

Experimental investigation on packed bed cool storage system for supply-demand management in building air-conditioning system suitable for micro thermal grid

In most of the developed nation, the increase in percentage share of renewable power in the total power generation causes major concerns over the integration of these renewable power with the grid resulting grid instability. Energy storage is a new frontier technology which is considered as the ultimate solution in developing micro-smart grid with distributed renewable power generation. Most of the hot countries like India spend nearly 24% of the electricity generated on air-conditioning and food preservation. Under such scenario, among the various types of storage systems, the cool thermal storage plays a vital role to promote renewable power in an economical way. Considering the importance in the present renewable energy scenario, in the present work, an experimental investigation was performed on a packed bed cool storage system integrated with a chiller system which has major advantages in central air-conditioning system for demand management strategies. The storage system consists of encapsulated spherical balls filled with a mixture of distilled water and pseudomonas (nucleating agent) as phase change material and a mixture of distilled water and mono-ethylene glycol as heat transfer fluid. The essential parameters such as reduction in subcooling, instantaneous, and cumulative heat transfer during the charging process are presented for the efficient operation.

Thermal analysis of hollow clay bricks submitted to a sinusoidal heating

The aim of the present work is to study numerically, in a transient state, the thermal behavior of three types of hollow bricks mostly used in the construction of building walls in Morocco. The coupled heat transfer by conduction through the surrounding walls, natural convection and surface radiation is taken into account. The outside vertical surface is submitted to a sinusoidal thermal excitation, while the inside vertical surface is maintained at a constant temperature. The top and bottom horizontal sides are assumed to be adiabatic. The governing equations for conservation of mass, momentum and energy are discretized by the finite volume approach and solved by the SIMPLE algorithm. The main parameters governing the problem are the amplitude, the period of the exciting temperature and the emissivity of the walls. The effect of these parameters on the global heat transfer through each structure is presented and examined. The results report that the hollow brick of type 3 allows a good reduction of heat transfer from exterior to interior surfaces of the building walls and hence providing an adequate thermal comfort. The emissivity of the internal surfaces affect considerably the heat transfer through the hollow bricks. The use of low emissivity materials on internal surfaces of the hollow bricks would greatly help in improving the energy consumption in buildings.

Exergoeconomic analysis of a geothermal steam turbine combined with multi-effect desalination and reverse osmosis

An exergoeconomic analysis is reported of a geothermal-based combined system for electricity and freshwater in which a geothermal steam turbine is integrated with multi-effect desalination and reverse osmosis systems. The article includes an exergy analysis, an economic assessment and an exergoeconomic (i.e., exergy-based economic) evaluation. The specific exergy costing method is used for the analysis of the system to determine the effects of various design criteria on the cost rates and then to incorporate feasible improvements for enhanced cost effectiveness. The results of the exergoeconomic analysis can assist in the design, optimization and improvement of geothermal-based electricity-freshwater production combined systems. It is found that the exergoeconomic factors for the reverse osmosis, multi-effect desalination and steam turbine are high, all exceeding 85%. Thus, reducing the investment costs for these components is merited. This can be done by any of the following measures, among others: reducing heat transfer area in the multi-effect desalination system, using less expensive pumps and membranes in reverse osmosis, and lowering the expansion ratio, turbine inlet temperature and isentropic efficiency for the steam turbine.

Field Measurements Validate Transient Annular Pressure Buildup Model

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 199561, “Validation of Transient Annular Pressure Buildup (APB) Model Predictions With Field Measurements in an Offshore Well and Characterization of Uncertainty Bounds,” by Rahul Pai, Anamika Gupta, and Udaya B. Sathuvalli, Blade Energy Partners, et al., prepared for the 2020 IADC/SPE International Drilling Conference and Exhibition, Galveston, Texas, 3-5 March. The paper has not been peer reviewed. The average geothermal gradient in the subject deepwater field in Nigeria is 4.37°C/100 m, nearly twice the gradient in most fields. As a result, the magnitude of the expected annular pressure buildup (APB) during steady-state production is large enough to threaten well integrity. Therefore, an insulating packer fluid (IPF) was used in Annulus A to reduce heat transfer to the outer annuli and to regulate the APB within acceptable values. The complete paper reports the results of a study that compares the temperature and pressure measurements from these wells with model predictions. Introduction Though APB has been studied by well designers for decades, the use of downhole measurements to study APB has been somewhat limited. Previous uses of downhole instrumentation to study APB phenomena principally have centered on monitoring the magnitude of the APB and managing the risk. None, as far as the authors are aware, use the results gathered from downhole measurements to verify the results of the models that routinely are used in the design of the wellbore tubulars and APB-mitigation technologies. Notwithstanding the wealth of literature on the subject of APB, several crucial and fundamental questions remain unanswered. Chief among these are: What is the accuracy of thermal-model temperature predictions during various well operations? How do temperature uncertainties influence APB predictions? When APB magnitudes are large enough to require installation of APB mitigation devices? How do the mitigation devices perform over the life of the well? The complete paper seeks to address these questions through an examination of downhole pressure and temperature measurements and a parallel analysis of model predictions. Furthermore, field data and model predictions are juxtaposed, sources of uncertainties in the measurement data and model inputs are considered, and overall uncertainties in the APB predictions (i.e., model estimates) are characterized.

Implementation of a cooling system to develop experimental fatigue tests below zero grades Celsius

Temperature is one of the matter properties with the greatest influence on the materials behavior existing in nature and those man designed. This physical magnitude allows to demonstrate and define behaviors and materials characteristics in the industry in general. Its influence is present in all the places where the materials fulfill functions, however, in some applications its influence is very little, which allows to disregard its effects. In the steels case (one of the most used materials at the industrial level today), the temperature variation produces dilation or contraction, depending on the temperature magnitude and its variation that affects them. Temperature increases generate an expansion phenomenon in the materials, which under load will reach a point where they present thermal fatigue failure. The opposite is that of temperature drops, where the phenomenon that occurs is contraction, often leading to the loss of adjustments and interference that compromise the equipment functionality and integrity. The fatigue failure mentioned is presented as a result of the stresses and deformations present in both cases. It is desired to condition a rotational flex fatigue test equipment with a cooling system to bring the sample material to temperatures below zero degrees Celsius, in order to check how low temperatures, affect the resistance of steel to fatigue. For this, a cooling system was designed and the fatigue equipment was adapted to reduce heat transfer. After carrying out this implementation and determining that the sizes of the devices were suitable for the proposed purposes, the initial temperature tests were carried out and, once this part was achieved, three repetitions of a rotary fatigue test were performed that demonstrated that the equipment can operate normally.

The Impact of Nanofluids on Droplet/Spray Cooling of a Heated Surface: A Critical Review

Cooling by impinging droplets has been the subject of several studies for decades and still is, and, in the last few years, the potential heat transfer enhancement obtained thanks to nanofluids’ use has received increased interest. Indeed, the use of high thermal conductivity fluids, such as nanofluids’, is considered today as a possible way to strongly enhance this heat transfer process. This enhancement is related to several physical mechanisms. It is linked to the nanofluids’ rheology, their degree of stabilization, and how the presence of the nanoparticles impact the droplet/substrate dynamics. Although there are several articles on droplet impact dynamics and nanofluid heat transfer enhancement, there is a lack of review studies that couple these two topics. As such, this review aims to provide an analysis of the available literature dedicated to the dynamics between a single nanofluid droplet and a hot substrate, and the consequent enhancement or reduction of heat transfer. Finally, we also conduct a review of the available publications on nanofluids spray cooling. Although using nanofluids in spray cooling may seem a promising option, the few works present in the literature are not yet conclusive, and the mechanism of enhancement needs to be clarified.

An experimental assessment of bio-mixed-phase change material in a lightweight compartment and its potential as latent energy storage in north-east climate of India

ABSTRACT The temperature fluctuations in a room directly influence the heating and cooling load of buildings and their energy consumption rate. To manage thermal loading, the use of passive technologies is in a recent trend with the application of Phase-changing materials (PCM). The major problem of material availability in a developing country is solved with the mixing of two easily available phase change materials. Paraffin is better in latent storage and palm oil with the low melting application is combined in definite proportion. In this experimental work, Paraffin-based Palm oil (7030) mixed Bio PCM is studied incorporating in a two small-scaled compartment. The first compartment is a reference room with insulation and the other with addition to a 20 mm PCM layer. The temperature fluctuation is studied with two cases of the orientation of the window. It is found that the average reduction in temperature fluctuation is found to be in the range of 1–2 C and maximum peak temperature reduction of 3 C and minimum peak temperature gain of 2 C is achieved, also heat transfer reduction through the walls is 4046% with PCM incorporation which is comparable to most recent works on different phase change materials and satisfies the energy storage potential of Bio PCM.

Experimental Validation of a Portable Power and Cooling System Using Integrated TEG-ORC

A waste heat recovery system consisting of a hybrid power and cooling cycle is described in this paper. It couples a thermoelectric generator (TEG) and an organic Rankine cycle driving a vapor compression cycle to implement heat activated power and cooling. The system was designed, developed, and tested under laboratory conditions using a hot air source simulating a heavy-vehicle exhaust stream. The hybrid or so-called cofunctional power and cooling system was designed to approach the size of a fieldable unit for testing with mobile diesel generators or heavy-vehicle exhaust streams, which have strict requirements for size, weight, and efficiency. As a result, microchannel heat exchangers were used extensively throughout the system design. High-temperature bismuth telluride () thermoelectric (TE) modules were used, and the TEG section contained 20 modules in two distinct electrical strings sandwiched between microchannel cold-side and hot-side heat exchangers. The cofunctional system has shown stable operation during tests conducted at various incoming hot air temperatures up to 388°C, simulating common heavy-vehicle exhaust stream conditions. Although the TEG power output was significantly lower than the design value because of reduced heat transfer into the TE modules due to contact area mismatch and significant heat loss, many system performance parameters reached or even exceeded the target values at design conditions. Design modifications are being implemented to incorporate custom-designed TE modules into the system and to reduce the TE cold-side temperature to improve the TEG output.

Effect of mist/steam uniformity on heat transfer characteristics in unconfined jet impingement

This paper presents the numerical investigations of the injection of mist into an unconfined cooling steam jet to analyze the effects on the corresponding heat transfer characteristics. The infusion of mist into an confined cooling steam jet demonstrates a remarkable improvement in the heat transfer specifications as described in numerous previous studies. Therefore, the current research contributes to the knowledge by focusing on the uniformity configurations of the injected second phase to the unconfined regions and the influence of the surrounding environment on the mist injected. Several variables govern the physical model of the mist concentration and jet to plate distance, which is included in three-dimensional incompressible Navier-Stokes flow with the discrete phase model for the multiphase flow regime. The simulation was conducted over a range of common working Reynolds numbers. The results show that controlling the uniformity of the injected mist will redefine the cooling characteristics. The accumulated mist near the edge leads to the heat transfer enhancement at H/D = 2, 4, and 6. The surrounding environment had a significant influence on the droplet behavior at H/D = 8, thus causing a heat transfer reduction of 8%. The droplet Stock number can determine the droplet performance on the target wall and introducing mist generates a third heat transfer peak that results in an average increase of 38% for 1% mist.