Outlet Height Research Articles

Evaluation of Child Anthropometries in Relation to Modern Vehicle Seat and Booster Dimensions

<div class="section abstract"><div class="htmlview paragraph">This study compared modern vehicle and booster geometries with relevant child anthropometries. Vehicle geometries (seat length, seat pan height, shoulder belt outlet height, and roof height) were obtained for 275 center and outboard rear seating positions of US vehicles (MY 2009–2022). Measurements of 85 US boosters (pan height and pan length) and anthropometries of 80 US children between 4–14yo (seated height, thigh length, leg length, and seated shoulder height) were also collected. Comparisons were made between vehicles, boosters, and child anthropometries. Average vehicle seat lengths exceeded child thigh lengths (+9.5cm). Only 16.4% of seating positions had seat lengths less than the child thigh length mean+1SD. Even for children at least 145cm, only 18.8% had thigh lengths greater than the average vehicle seat length. Child thigh lengths were more comparable with average booster seat pan lengths for all multi-mode and high-back designs (-2.0cm) and low-back boosters (+3.1cm). The average observed booster pan height (9.9cm) would help most children achieve seated shoulder heights similar to the Hybrid III 5th percentile Female ATD. Compared to vehicle seats, booster geometries were more compatible with child thigh lengths and assist children in achieving seated shoulder heights more comparable to the vehicle restraint system. This emphasizes the continued need for shorter vehicle seat cushion lengths for these occupants and the need to educate caregivers and promote booster recommendations which highlight the importance of achieving proper belt fit and avoiding slouched postures, even for children greater than 8 years and/or 145cm.</div><div class="htmlview paragraph"/></div>

Effect of tapered porous ribs on the performance of Proton exchange membrane fuel cells

The conventional trench ridge structure suffers from the difficulty of removing liquid water and poor gas transport performance. The water removal and gas transport performance inside the flow field are enhanced by introducing a tapered porous rib flow field (TPRFF). In order to investigate the performance of TPRFF, a complex three-dimensional, multiphase, non-isothermal agglomeration model was developed using numerical techniques. The numerical results show that the TPRFF exhibits significant improvements in oxygen concentration distribution, oxygen distribution uniformity and water removal compared to a conventional parallel flow field (CPFF). In addition, the dissolved water content remained almost constant while the liquid water saturation was lower. The study also investigated the effect of different cathode exit heights on the performance of the fuel cell using TPRFF. The results showed that the net power density increased by 14.0 %, 11.9 %, 8.7 %, and 1.5 % for outlet heights of 1.3 mm, 1.0 mm, 0.7 mm, and 0.4 mm, respectively, while it decreased by 27 % for an outlet height of 0.1 mm. Finally, the effect of different stoichiometric ratios on cell performance was also investigated in the novel flow field.

Using the Taguchi Method and Grey Relational Analysis to Optimize Ventilation Systems for Rural Outdoor Toilets in the Post-Pandemic Era

This study addresses the issue of poor air quality and thermal comfort in rural outdoor toilets by proposing a ventilation system powered by a building-applied photovoltaic (BAPV) roof. A numerical model is established and validated through comparison with the literature and experimental data. Based on a consensus, four influential variables, namely, inlet position, outlet height, supply air temperature, and ventilation rate, are selected for optimization to achieve multiple objectives: reduction in ammonia concentration, a predicted mean vote (PMV) value of 0, minimization of age of air, and energy consumption. The present study represents a pioneering effort in integrating the Taguchi method, computational fluid dynamics (CFD), and grey relational analysis to concurrently optimize the influential variables for outdoor toilet ventilation systems through design and simulation. The results indicate that all four variables exhibit nearly equal importance. Ventilation rate demonstrates a dominant effect on ammonia concentration and significantly impacts the age of air and energy consumption, while supply air temperature noticeably influences PMV. The optimal scheme features an inlet at center top position, an outlet height of 0.2 m, a supply air temperature of 12 °C and a ventilation rate of 20 times/h. This scheme improves ammonia concentration by 18.9%, PMV by 6.8%, and age of air by 30.0% at a height of 0.5 m, while achieving respective improvements by 18.9%, 5.5%, and 22.2% at a height of 1.5 m. The BAPV roof system generates an annual electricity output of 582.02 kWh, which covers the energy consumption of 358.1 kWh for toilet ventilation, achieving self-sufficiency. This study aims to develop a zero-carbon solution for outdoor toilets that provides a safe, comfortable, and sanitary environment.

Performance evaluation of film holes used for cooling the optical window of a sensor probe

In this paper, three types of film holes (namely cylindrical hole, round-to-slot hole, slot hole) are applied to provide cooling protection for a sensor probe’s optical window while considering the structural size limitations. The film cooling performance, discharge coefficients and pressure drop of three types of film holes are discussed and compared in terms of both the blowing ratios and the outlet heights of the film holes through numerical simulation. The results demonstrate that, compared to the cylindrical holes, the round-to-slot holes and slot holes exhibit significantly improved film coverage performance. Among these, the RTSH-0.6 hole exhibits the best comprehensive performance, the film cooling effectiveness of the RTSH-0.6 hole is higher than 0.99 under all three blowing ratios with the lowest pressure drop ratio less than 0.5.

Numerical study on smoke temperature and exhaust efficiency in electric cable tunnel

Cable tunnels are the lifeline of cities. Once a serious fire occurs on cables, the toxic smoke generated by cable combustion spreads and escapes, causing serious harm to the surrounding environment and personnel. The heat generated can also ignite nearby combustibles, causing casualties and property damage. Based on the above issues, using fluid dynamics methods, fire dynamic simulation was used to simulate cable tunnel fire scenarios under four variables: wind speed, fire source power, smoke outlet height, and smoke exhaust airflow. The temperature distribution law of the ceiling smoke layer inside the cable tunnel, smoke generation law, tunnel smoke exhaust efficiency, and other factors were clarified, revealing the impact mechanism of the above factors on tunnel fire smoke exhaust efficiency and smoke performance improvement methods. The research results indicate that the combination mode of exhaust air volume and ventilation air speed can effectively control tunnel fire smoke, providing a reference for the fire prevention design of cables in urban cable tunnels.

Multi-objective optimization design of scramjet nozzle based on grey wolf optimization algorithm and kernel extreme learning machine surrogate model

This study delves into the parametric design of the scramjet nozzles, utilizing the Catmull–Rom curve, to meet the high-performance design requirements. It establishes a high-dimensional, multi-objective optimization design method based on a surrogate model for the nozzle. In addition, this research proposes a surrogate model for nozzle performance to enhance the accuracy of the traditional surrogate model and prevent the multi-objective optimization design method from optimizing in an incorrect direction. This model incorporates the grey wolf optimization (GWO) algorithm and kernel extreme learning machine (KELM). Various machine learning algorithms are compared and analyzed, demonstrating that the performance parameters predicted by the GWO-KELM model are the most accurate, and the generalization of GWO-KELM is verified. Utilizing the particle swarm optimization algorithm assisted by GWO-KELM, the multi-objective optimization of the nozzle is further investigated. This study obtains the optimal Pareto front, analyzes the distribution of design variables in the Pareto solution set, and reveals the impact of geometric parameters on nozzle performance. Comparing the representative nozzle from the Pareto front with the truncated maximum thrust nozzle, it is found that the thrust, lift, and outlet Mach number increase by 3.3%, 12.2%, and 0.5%, respectively, while the outlet height decreases by 5.3%. This research contributes to overcoming the limitations of traditional design methods, which are typically time-consuming. The proposed GWO-KELM surrogate model effectively tackles the issue of low prediction accuracy.

Lubrication approximation of pressure-driven viscoelastic flow in a hyperbolic channel

We investigate theoretically the steady incompressible viscoelastic flow in a hyperbolic contracting channel. The fluid viscoelasticity is modeled using the upper convected Maxwell (UCM), Oldroyd-B, Phan-Thien and Tanner (PTT), Giesekus, and the finite elasticity non-linear elastic dumbbell with the Peterlin approximation (FENE-P) models. We first develop the general governing equations for flow within a non-deformable channel whose cross section varies with the distance from the inlet. We then exploit the classic lubrication approximation, assuming a small aspect ratio of the channel to simplify the original governing equations. The final equations, which we formulate in terms of the stream unction, are then solved analytically using a high-order asymptotic scheme in terms of the Deborah number, De, and the formulas for the average pressure drop are derived up to eight orders in De. The accuracy of the original perturbation solution is enhanced and extended over a wide range of parameters by implementing a convergence acceleration method for truncated series. Furthermore, convergence of the transformed solutions for the average pressure drop is demonstrated. The validity and accuracy of the theoretical results is independently confirmed through comparison with numerical results from simulations performed using high-order finite differences and pseudospectral methods. The results reveal the decrease in the average pressure drop with increasing the Deborah number, the polymer viscosity ratio, and the ratio of the inlet to the outlet height. We also show that the fundamental UCM and Oldroyd-B models can predict the major viscoelastic phenomena for this type of internal and confined lubrication flows, while the effect of the rheological parameters of the PTT, Giesekus, and FENE-P models on the results is minor.

Experimental study on the combustion performance of a turboshaft engine annular combustor

Efficient application of trapped vortex combustion technology is a hotspot in the aerospace field. This paper describes a turboshaft engine combustor based on this technology, named as mixed-flow trapped vortex combustor (MTVC). MTVC utilizes stable vortex structure formed in cavity to promote combustion stability. RP-3 aviation kerosene required for combustion is directly injected into cavity, which continuously supplies energy to combustor. Combustion performance of MTVC with different inlet aerodynamic parameters and fuel-air parameters was studied experimentally on full-ring test rig, including combustion efficiency, pressure loss and outlet temperature profile. According to the experimental findings, MTVC has very high combustion efficiency under the testing conditions of this paper, all exceeding 96%. Pressure loss coefficient is positively correlated as the square of inlet Mach number. Pressure distribution of MTVC is largely consistent with inlet velocity. Outlet temperature profile is not a straight line at radial height, showing a distribution trend of high temperature in the middle of combustor outlet, and low temperature at both ends of combustor outlet. Peak temperature is essentially at 0.6 times combustor outlet height. There is a cyclical variation in circumferential direction. The variation between combustion efficiency and aerodynamic parameters is also obtained in this paper.

Numerical analysis of solid phase hydrodynamics in a continuous precipitator relevant for plutonium reconversion

The extensive application of solid-liquid flow in various industries, has made it important to comprehend the hydrodynamics inside different process equipment and optimize their operation. In the present work, solid phase hydrodynamics in a continuous precipitator relevant for plutonium (Pu) reconversion has been investigated numerically. Euler-Euler two-fluid simulations were performed to analyse the performance by varying the solid concentration (5, 10, 15, and 20 g/l), impeller speed (500 and 700 rpm) and overflow outlet height (0.65, 0.75 and 0.85 m). The solid phase behaviour in precipitator is analysed by comparing the solid volume fraction and pressure distributions along the height. To enable easy handling of precipitator inside glove-box, the solid mass, volume rate and pressure distributions through overflow outlet at different height is thoroughly investigated. Further, the effect of solid concentration and rotating speed of impeller on radial velocity distribution is analysed. The results show that overflow of solid phase is dependent on dispersed phase concentration and rotating speed of the impeller. Further, the increase in overflow outlet height increases the overflow time. However, the volume fraction of solid remains constant during the steady operation. The study will be helpful to design a glove-box adaptable precipitator for continuous plutonium reconversion.

Comparative studies and optimizations of air distribution of underground building ventilation systems based on response surface methodology: A case study

As underground enclosed buildings, utility tunnels have limited ventilation conditions. An efficient ventilation system is necessary for improving the indoor thermal environment and air quality in utility tunnels. In this paper, exhaust fan ventilation (EFV), relay fan ventilation (RFV), and innovative wall-attached ventilation (WAV) schemes are compared using a series of evaluation indicators (i.e., energy efficiency coefficient, nonuniform coefficient, temperature not guaranteed rate, and age of air). The results show that the WAV scheme offers a higher ventilation efficiency, while decreasing the age of air and providing a uniform air distribution. Thus, the WAV scheme is recommended for utility tunnel ventilation systems. Additionally, the WAV scheme is further optimized and analysed based on response surface methodology (RSM). The influence of different factors (i.e., the slot outlet height (h), slot outlet width (b), air-supply velocity (u0), and cable heat source intensity (q)) on the evaluation indicators is studied, and the optimal design scheme (h = 1.40 m, b = 0.12 m, u0 = 3.00 m/s, q = 74.5 W/m2) is obtained and verified. The age of air in the optimal design scheme is 486.50 s. This paper can provide a reference for the ventilation design of urban underground buildings.

Effects of proactive phantom cooling on turbine endwall aerodynamic and film cooling performances considering aggressive swirling inflow

The turbine vane endwall downstream of the lean premixed combustor operates in an extremely complicated environment resulting from strong swirling inflow. Consequently, advanced cooling methods should be developed considering aggressive swirling inflow conditions. In the current work, the numerical results indicated that the swirling inflow seriously deteriorated the film cooling level by more than 30%, especially near the pressure side endwall, and it increased the total pressure loss of the vane passage by up to 80%. According to the endwall aerothermal performance under the swirling inflow conditions, the proactive phantom cooling method was presented. With the help of the endwall secondary flow, the proactive phantom coolant could obviously increase the film cooling effectiveness on the endwall and the vane pressure side surface at the same time. Furthermore, the effects of the outlet height and the mass flow rate on the performance of proactive phantom cooling were investigated. The design with h/H = 4.0% and MFR = 0.30% was found to be the best choice in this study with the largest film cooling coverage area and a 44% increase of the overall film cooling effectiveness. This paper provides a novel cooling method to increase the endwall film cooling performance under swirling inflow conditions.

A semi-analytical model for predicting outflow concentration of vented turbidity currents with application in the Xiaolangdi reservoir

Turbidity current venting is an important way to reduce reservoir sedimentation. Existing methods to predict the outflow concentration of vented turbidity currents either depend on three-dimensional (3D) modelling with high computational cost or semi-empirical equation with a simple assumption of uniform velocity distribution. This study presents a semi-analytical model for predicting outflow concentration in turbidity current venting events, which accounts for the non-uniform and asymmetric velocity distribution in the withdrawal layer. Firstly, a 3D numerical model is established to facilitate the determination of withdrawal layer thickness and extraction of flow velocity within it, which is validated by simulating a group of venting experiments in the literature. Then, a velocity distribution equation for turbidity currents insusceptible to downstream disturbance is found to be applicable in the withdrawal layer, after relating the parameter controlling the velocity profile shape with the ratio of the outlet height to the layer thickness. Finally, the equation is derived for the relative concentration of outflow to the turbidity current concentration before the dam, whose solution is dependent on the proposed velocity distribution. Field measured data in the Xiaolangdi Reservoir and operation records of sediment release structures were collected and used to validate the model. A concept of nominal outlet width is proposed in order to apply the model in reservoirs with complex water releasing structures, which is calibrated along with the dimensionless parameter in the withdrawal layer thickness equation. The proposed model can help to optimize the design of sediment release structures and improve the venting operation.

Experimental investigation on supersonic film cooling of hypersonic optical dome under different nozzle pressure ratios

When an aircraft flies at hypersonic speeds in the atmosphere, its optical window is subjected to severe aerodynamic heating. To investigate the supersonic film cooling laws of hypersonic optical dome, three supersonic (Mach 2.35) film generation devices with different jet outlet heights (1 mm, 2 mm, 3 mm) were designed. The experiments were conducted in a hypersonic (Mach 7.1) gun wind tunnel. The NPR (nozzle pressure ratio = jet outlet static pressure/nearby mainstream static pressure) ranged from 0 to 2.3. The heat flux on the window surface was measured by the thin film resistance thermometer. Experimental results indicate that, under different jet outlet heights, the film cooling effectiveness increased gradually as the NPR increased, corresponding to an increase in effective cooling length. The existing similarity parameters for film cooling could effectively predict the effective cooling length of supersonic film when NPR = 1. However, the prediction effect deviated significantly when NPR ≠ 1. Moreover, the effective cooling length corresponding to the unit mass flow rate of the coolant first increased and then decreased with the increase of NPR, and there existed an optimal solution. Furthermore, with the same coolant mass flow rate, higher jet Mach number lead to better supersonic film cooling performance.

Theoretical Analysis Method for Roll Motion of Popup Data Communication Beacons

The popup data communication beacon (PDCB) can send data to the shore and ships through the BeiDou navigation satellite system (BDS) when it surfaces. The data can be collected by a deep-sea landing vehicle (DSLV) and transmitted using a magnetic induction coil. PDCBs can reduce the cost of DSLV recovery and redeployment. Whether the data can be successfully sent mainly depends on the outlet height and roll angle of the PDCB. Thus, accurately assessing the effect of the roll angle on data transmission is crucial. In this study, first, the differential equation of roll motion was preliminarily established using the small-amplitude wave theory along with the shape characteristics of the PDCB. Next, the nonlinear term of the recovery moment was processed using the Linz Ted Poincaré method. Then, the wave current force was analyzed using the Morrison theoretical formula along with an additional inertia moment calculation formula that is suitable for slender cylindrical small buoys. Finally, the theoretical calculation results were verified using the computational fluid dynamics (CFD) method and pool test. The roll angle error of the theoretical calculation was within 5%. Thus, the heave and roll response of PDCBs can be evaluated using theoretical calculation methods. The proposed calculation formula of additional inertia moment has guiding significance for the further optimization of the structure.

A numerical investigation of a photovoltaic thermal system contained a trapezoidal channel with transport of silver and titanium oxide using the water as base fluids

This article presents a numerical investigation of forced convection in a PV/T system to reduce the temperature caused by solar radiation, which can decrease its electrical energy production. The study uses two types of nanoparticles, namely titanium oxide and silver, combined with water as the base fluid. The PV/T system features a trapezoidal flow channel, and the Navier-Stokes and energy equations are solved using the COMSOL Multiphysics 6.0 finite element-based computer code to obtain an approximate solution. The study tests the range of Reynolds number, aspect ratio, and the volume fraction of both nanoparticles as (100–1000), (0.4–1), and (0.01–0.25), respectively, to analyze the various impacts of the selected variables on the percentage change in cell temperature and efficiency by varying the Reynolds number and aspect ratio between the inlet to the outlet height of the flow channel. The results indicate that increasing the Reynolds number from 100 to 1000 can reduce cell temperature by 50% and increase cell efficiency by 4.4%. Similarly, changing the aspect ratio from 0.4 to 1 can reduce the percentage temperature of the cell due to inlet temperature by 26.2% and increase cell efficiency by 1.6%. The study reveals that increasing the outlet height while fixing the outlet height of the channel can improve cell performance. Additionally, increasing the volume fraction of both nanoparticles in the base fluid can enhance the cell efficiency of the PV/T system.

Multiphase, three-dimensional PEM fuel cell numerical model with a variable cross-sectional area flow channel

PurposeThis paper aims to investigate the impact of three different flow channel cross sections on the performance of the fuel cell.Design/methodology/approachA comprehensive three-dimensional polymer electrolyte membrane fuel cell model has been developed, and a set of conservation equations has been solved. The flow is assumed to be steady, fully developed, laminar and isothermal. The investigated cross sections are the commonly used square cross section, the increasingly used trapezoidal cross section and a novel hybrid configuration where the cross section is square at the inlet and trapezoidal at the outlet.FindingsThe results show that a slight gain is obtained when using the hybrid configuration and this is because of increased velocity, which improves the supply of the reactant gases to the catalyst layers (CLs) and removes heat and excess water more effectively compared to other configurations. Further, the reduction of the outlet height of the hybrid configuration leads to even better fuel cell performance and this is again because of increased velocity in the flow channel.Research limitations/implicationsThe data generated in this study will be highly valuable to engineers interested in studying the effect of fluid cross -sectional shape on fuel cell performance.Originality/valueThis study proposes a novel flow field with a variable cross section. This design can supply a higher amount of reactant gases to the CLs, dissipates heat and remove excess water more effectively.

Assessment of Basin Morphometric Measurements Accuracy Based on Different DEM Data, Chai Dakuk Basin, Northeast Iraq: A Case Study

Morphometric analysis is essential in evaluating the geomorphological development and hydrological characteristics of rivers and valley basins. Several studies used different DEM data to evaluate elevation accuracy or their impact on measurements of limited morphometric parameters. The current study was carried out on the Chai Dakuk River basin in the northeastern part of Iraq. The basin is bounded by latitudes 34°44'30"- 35°35'49"N and longitudes 44°17'39"- 45°28'16"E. The current study aims to evaluate the accuracy of different DEM data, i.e., ASTER-GDEM 1-arcsec, SRTM 1-arcsec, and 3- arcsec, ALOS-12.5 meters, and GMTED 7.5 arcsec data, based on reference points collected by GPS and top maps of scale 1: 20000, and to evaluate DEM resolution on the calculation accuracy of different morphometric parameters. The analysis of morphometric parameters was carried out using ArcGIS- morphometric toolbox. The results of the accuracy assessment of DEM data identified the SRTM 1arc-second is more adequate with reference measurements; based on that, the measurements of all other DEM are compared to the SRTM 1- arcsec. The results of morphometric parameters show noticeable differences in many morphometric parameters calculated from different DEM data. Numbers and lengths of stream orders; bifurcation ratios; main channel length; drainage density; stream frequency; constant of channel maintenance; compactness coefficient; drainage texture; infiltration number; basin outlet height and the maximum height of basin, total basin relief, and ruggedness number. According to the results, the study concluded that the SRTM 1- arcsec data are more suitable for morphometric analysis, followed by ASTER GDEM data.

Characterizing the induced flow through the cavity of a wall solar chimney under the effects of the opening heights

Using solar chimneys in buildings can enhance the thermal insulation of the building envelope and provide sufficient ventilation and cooling. The performance of a solar chimney is strongly affected by its configurational factors. This work examines the effects of the opening heights on the flow field in the cavity of a wall solar chimney with a Computational Fluid Dynamics (CFD) model. Both cases of equal and unequal opening areas were considered. The results show that the induced flow rate increases with the opening height and gradually becomes constant as the opening height is about 2.0–3.0 and 5.0–6.0 times the air gap for heating the left wall (HLW) and the right wall (HRW) of the air cavity, respectively. Particularly, using equal inlet and outlet heights that are equal to the air gap reduces the flow rate of 27% for HLW and 85% for HRW compared to the maximum ones. The optimal design of a wall solar chimney to achieve maximum flow rate is proposed for two cases of heating, that is, (a) for HLW, equal opening heights which are twice the air gap, and (b) for RHW, the inlet height equal to the air gap, and the outlet height equal to five times the air gap.

Perimembranous ventricular septal defect with left ventricular volume overload: Features of patients in the French Cohort Study (FRANCISCO)

Management of perimembranous ventricular septal defect (pmVSD) with left ventricle (LV) volume overload (Zscore of end diastolic LV diameter (LVEDD) > 2) without pulmonary arterial hypertension remains controversial. Our objective was to describe features of patients in the FRANCISCO registry, a prospective nationwide cohort study. Data were collected at inclusion. Echocardiographic data were cross-checked by a Core-lab. A total of 212 patients with a median age of 4-year-old [1; 13] have been included in 38 centres. LV was very dilated (Zscore of LVEDD > 3) in 38.6% of the study population with a relationship with maximum pmVSD size ( P < 0.01). Maximum pmVSD size was correlated with Zscore of LVEDD ( P < 0.01) and left atrial area ( P < 0.001). In patients aged 1 to 2 yo ( n = 87; 41%), dyspnoea (26%) was associated with a lower weight ( P < 0.001), left atrial area ( P < 0.01), medical therapy ( P < 0.01), a trend to a higher LVEDD Zscore ( P = 0.19) but not with pm VSD size. In 25.5% of cases, pmVSD were closed by catheterization or surgery, with management varying among French regions ( P < 0.001). PmVSD closure was performed in 19 children aged 1 to 2 yo (22%), in 23 children aged 3 to 15 yo (27%) and in 12 patients over 15 yo (29%), P = 0.6 ( Fig. 1 ). Factors associated with pmVSD closure were maximum pmVSD size in all patients ( P < 0.001); dyspnoea in children aged 1 to 2 yo ( P = 0.021); minor to mild aortic regurgitation ( P < 0.01), inlet or outlet pmVSD extension ( P < 0.01) and height of the membranous septal aneurysm ( P < 0.01) in children aged 3 to 15 yo; aortic cusp prolapse in patients over 15 yo ( P = 0.017). In France, pmVSD with LV overload are not systematically closed in patients above one year-old. Closure is mainly indicated in case of symptoms or associated anatomical lesions. Long-term outcomes are awaited to refine the therapeutic algorithm.

NUMERICAL STUDY OF THE EFFECTS OF EVAPORATIVE COOLER SUPPLY AIR OUTLET HEIGHT ON THERMAL COMFORT

Thermal comfort in a space equipped with a direct evaporative cooler is a function of the height of the cooler's supply air outlet. This article attempts to numerically investigate the impact of hybrid downdraft evaporative cooler (HDEC) supply outlet height on occupant thermal comfort in an office building. DesignBuilder CFD parametric simulations was carried out by varying the height of the HDEC supply outlet from 0.1m to 2.4 m, step 0.1 m above ground level, using Predictive Mean Vote (PMV) as an objective function. The results show that the best PMV of -0.27 was obtained at 0.4m above the floor level.