Heat Transmission Coefficient Research Articles

Resiliency evaluation of sheltering in a net-zero energy house during summer power outage

This study examines the growing issue of power outages caused by natural disasters and proposes the use of net-zero energy houses (ZEH) as a safe alternative to traditional shelters. A ZEH, equipped with an independent energy system, can maintain essential living standards such as thermal comfort and 24-hour air conditioning during a summer power outage, reducing the risk of heatstroke. The research tested a ZEH in Japan, confirming its ability to support critical household appliances like refrigerators, lighting, and water heaters for up to 72 h. This demonstrates the ZEH's potential for offering safe, comfortable shelter during emergencies while addressing problems like poor sanitation and lack of privacy found in typical shelters. The experimental ZEH is located in Shizuoka, Japan, is a steel structure, and has a floor area of 110.94 m2 and overall heat transmission coefficient (UA) of 0.48 W/m2·K. The ZEH was equipped with a 5.1 kW photovoltaic system and 5.6/11.2 kWh storage battery (BT), which produced an output of up to 2.0/4.0 kVA. A ZEH with a 5.6 kWh BT can provide for ventilation and living/dining room/kitchen air conditioning (AC), refrigerator, television, lighting, mobile phone charging, rice cooker, microwave, electric kettle, and heat pump water heater during a 72-h power outage. The ZEH with a 11.2 kWh BT can also provide bedroom AC and high-load home appliances for lunch and dinner, in addition to a 5.6 kWh BT. The use of AC in a self-supporting circuit maintained the thermal environment at a low heat stroke risk.

CFD Calculation of Natural Convection Heat Transmission in a Three-Dimensional Pool with Hemispherical Lower Head

The integrity of a pressure vessel (PRV) is affected by the decay heat of the molten pool in the lower head, so it is very important to study the natural convection heat transmission in the lower head. Scholars from all over the world have carried out a lot of experimental studies and calculations to determine the convection mechanism and heat transmission characteristics of the molten pool. Most of them were based on the empirical formula of convective heat transmission on the wall of a hemispherical molten pool based on two-dimensional slice experiments and simulation calculations. In this study, FLUENT 2021R1 software was used to simulate the three-dimensional convective heat transmission process of the hemispherical molten pool, and the temperature, velocity and wall heat transmission coefficients of the flow field were analyzed. The results were in good agreement with experimental data from UCLA (University of California, Los Angeles). Through research on the heat transmission of the lower head, the results showed that in the region where the wall angle was θ between approximately 72 and 90 degrees, heat transmission coefficients had larger fluctuations, and a more reasonable empirical relation was proposed. Comparing between the simulation results of CFD and the two-dimensional empirical formula, it was found that the latter one was smaller under the same θ angle condition. Finally, the convection phenomena of different external temperatures were simulated, and the main factors affecting the flow field by temperature were analyzed.

An Experimental Study of Porous Coated Hybrid Elliptical Tubes in Phase Change Heat Transfer

Abstract Porous coating over hybrid elliptical tubes are presented as the state-of-the-art in heat transmission during phase change maintaining its wide-ranging applicability. The saturated nucleate boiling heat transfer performance of porous coated hybrid elliptical tubes exposed to varying orientation angles is compared to that of conventional circular tubes in an accompanying experimental study conducted at atmospheric pressure. Four different copper porous coating thicknesses are varied from 34 µm to 128 µm with a heat flux range of 14.87-94.82 kW/m2. A greater coefficient of heat transfer is claimed for the coated hybrid elliptical tube compared to the uncoated circular tube, regardless of the orientation angle or coating thickness. The uncoated and porous coated hybrid elliptical tube provided a greater coefficient of heat transmission at 0° than at 90°. At 0° orientation angle, the coating with a thickness of 66 µm improve heat transmission by 1.27 - 1.5 times than that of uncoated surface while minimum enhancement about 1.16 - 1.24 times is found in 34 µm. Furthermore, a dimensionless semi-empirical correlation is established to predict own heat transmission coefficient findings within ±12%, independent of coating thicknesses and orientation angles.

Numerical solutions of steady radiative Maxwell-nanofluid flow toward a stretching sheet in the presence of magnetic field and porous medium

The study investigates the behavior of a Maxwellian nanofluid flowing steadily over an extending sheet in a permeable medium with a magnetic field. The energy equation includes the radiation, and the conservation of momentum equation considers the magnetic field and porous medium. The novelty of this study is in its examination of complex phenomena involving magnetic fields, radiation, Maxwell fluids, and nanoparticle suspensions in a porous medium via an exponential stretching sheet. The study of Maxwell fluids has been enriched by the substantial contributions made by researchers, delving into their rheological behavior, modelling, and applications. Their work has provided valuable insights into the complexities of these materials and has advanced the knowledge in this specialized area of fluid mechanics. The governing partial differential equations (PDEs) are converted into ordinary differential equations (ODEs) utilizing an appropriate similarity transformation. These resultant ODEs are then resolved by employing a numerical approach, specifically the finite element method. The numerical simulations provide valuable information regarding the distributions of velocity, temperature, and nanoparticle concentration. Furthermore, the presented tabulated outcomes display alterations in skin friction, mass transfer rate, heat transmission coefficients, and their reliance on different emerging parameters. The velocity diminishes as the magnetic field, suction, Maxwell fluid, and medium factors increase, while it enhances with the stretching sheet limitation. The temperature diminishes with the Prandtl number but upsurges with higher radiation, thermophoresis, and Brownian motion. As the thermophoresis limit increases, concentration rises, but it decreases with an upsurge in the Lewis and Brownian motion. The heat transfer rate rises with radiation, thermophoresis, and Brownian motion, but the mass transfer rate decreases with Lewes and Brownian motion. The outcomes of the study could have implications for various engineering and industrial applications that control and manipulate fluid flows and heat transfer.

Effect of the superthermal electrons on the heat flux through a magnetized sheath

A one-dimensional model, in which the ionization and collision are omitted in the Debye sheath region, is applied to investigate the effect of the superthermal electrons on the heat flux through a magnetized sheath. For different temperatures and concentrations of the superthermal electron, and magnitudes and directions of the magnetic field, the profiles of plasma parameters including ion density and flow velocity perpendicular to the wall, the background and superthermal electron densities, and sheath potential in the presheath region are calculated. The variation of the plasma density and sheath potential drop at the Debye sheath entrance with the superthermal electrons and magnetic field modifies the particle and heat fluxes across the Debye sheath to the material surface. The sheath heat transmission coefficient can increase significantly even for a very small superthermal electron population. The dependence of the sheath heat transmission coefficient on the magnetic field angle decreases with the contribution of the superthermal electron in a strong magnetized sheath. When investigation of the heat flux including the superthermal electrons to a water-cooled W/Cu monoblack for the tokamak divertor, compared to the case of without superthermal electrons, it is found that the increase in both heat flux to the material surface and surface temperature of the material is mainly due to the enhancement of the sheath potential drop caused by the superthermal electrons, but the increase in the latter is not as pronounced as the former.

DEM Investigation on the Flow and Heat Transmission Characteristics of Multi-Size Particles Mixed Flow in Moving Bed

The moving bed heat exchanger (MBHE) has been widely applied in the recovery of waste heat of industrial particles. Currently, investigations focus on uniform-size particles in the MBHE, but few studies are conducted on multi-size particles produced by industrial granulation. Therefore, based on the discrete element method (DEM), the heat transmission model of multi-size particles is established, and flow and heat transmission processes of typically normal distribution particles in the MBHE are studied. In conclusion, there are significant differences in particles tangential velocity and contact number in local regions of a heat exchanger pipe, resulting in different local heat transmission coefficients. In addition, the increases in outlet particle velocity and inlet particle temperature significantly enhance the heat transmission. When the outlet particle velocity grows from 1 mm/s to 5 mm/s, the overall heat transmission coefficient increases by 36.4%, and as the inlet particle temperature rises from 473 K to 873 K, the overall heat transmission coefficient increases by 16.1%.

THERMAL ANALYSIS OF BI-DIRECTIONAL FUNCTIONALLY GRADED PLATES SUBJECTED TO HEAT GENERATION

The two-dimensional steady-state heat transfer problem is analyzed under the most general boundary conditions in a heterogeneous environment. It is assumed that the internal heat generation varies arbitrarily in two directions, while the thermal conductivity coefficient of the material is bi-directly (thickness-length) graded with the Mori-Tanaka model. The linear inhomogeneous partial differential equations produced under these conditions may not be solved by conventional methods. The governing equation of the system is numerically solved with high accuracy using the 2D pseudospectral Chebyshev method. Benchmark problems are used to check the accuracy of the method. It has been observed that the effect of volumetric heat generation on the temperature distribution is more than the heat transmission coefficient. Besides, this method is simple and effective and can be easily applied to such problems.

DECARBONIZING A THAI COAL POWER PLANT: EFFECT OF FLUE GAS LOADS ON CARBON CAPTURE PERFORMANCE AND ECONOMICS

This study investigated the impact of a cylindrical obstacle on convection in an inclined square cavity filled with water-Al2O3 nanofluid. Using the finite volume method, the problem was resolved by having the inner cylinder rotate adiabatically while other walls were thermally insulated. Additionally, the bottom wall was hotter than the top. The study examined the effects of cylindrical obstacle radius (0.1 ≤ R ≤ 0.2), rotation speed (-500 ≤ Ω ≤ 500), Richardson number (0.01 ≤ Ri ≤ 100), volumetric nanoparticle fraction (0.02), and Grashof number (Gr=104) on heat transfer rate or Nusselt number. The results were compared with previous literature, and the influence of the cylindrical obstacle rotational speed on convection flow was evaluated. An increase in the counterclockwise angular rotating speed resulted in higher nanofluid flux. The heat transmission coefficient increased as the Richardson number decreased. The use of nanofluid in the enclosure increased the coefficient of heat flow through mixed convection. Finally, the study showed that the convection heat exchange is enhanced with the increase in the radius. Moreover, an enhancement of the Nusselt number around 46% was reported for the cylinder, under Gr=10000, ∅=0.02, γ=45° and Ri=10.

Optimizing Window Glass Design for Energy Efficiency in South Korean Office Buildings: A Hierarchical Analysis Using Energy Simulation

The world is emphasizing the need for building design that considers energy performance to deal with climate problems. South Korea has constantly been tightening the design standards for saving building energy but with a focus on thermal performance and equipment systems. Accordingly, this study conducted an energy simulation experiment on office buildings with different window-to-wall ratios (WWRs) to propose a smart glazing plan to improve energy performance. An energy simulation experiment was performed on office buildings with varying WWRs to hierarchically analyze the influence of building window performance elements, including the heat transmission coefficient (U-value), visible light transmittance (VLT), and solar heat gain coefficient (SHGC), on building energy performance. The analysis showed that SHGC had the most significant impact on the heating and cooling load, by 22.13%, with the influences of the variables being 12.4% for the U-value, 4.78% for VLT, and 82.83% for SHGC. The results showed that the solar heat gain coefficient (SHGC) had the greatest impact on energy performance among window performance elements, and the effect increased significantly in certain WWRs. Moreover, to improve the energy performance of buildings with higher WWRs, it is essential to reflect the optimum composition of the U-value and SHGC on the window plan. This study’s findings propose measures to supplement existing window plans focusing on thermal performance. Furthermore, these results hold academic value in providing concrete grounds for that.

Global mathematical correlations for heat pipe and nanofluid based thermal energy storage system: Dimensional analysis approach

AbstractThis research article presents the development of a mathematical model for a nanofluid‐based thermal energy storage (TES) system. The main objective of the study is to establish global correlations among various performance parameters of the TES system. The TES system considered in this research employs Al2O3/Soybean oil as the heat transfer fluid (HTF), and heat pipes are integrated to enhance heat transfer between the HTF and the phase change material. The mathematical model developed in this study is based on the Buckingham‐pi theorem. The derived correlations encompass the Nusselt number, stored energy, and thermal efficiency. Validation of the model is conducted for the Nusselt number, and a regression analysis is performed to assess the accuracy level of the mathematical model. Using the derived mathematical models, several key parameters of the TES unit are calculated. The convective heat transmission coefficient is determined to be 364.07 W/m2K, indicating the efficiency of heat transfer within the system. The thermal efficiency is found to be 89.10%, which provides insights into the overall effectiveness of the TES unit. Additionally, the thermal storage capacity of the TES unit is calculated as 3425.68 kJ, representing the amount of energy that can be stored and retrieved by the system. By equating the dimensions of variables within an equation, it becomes possible to deduce the relationship between the unknown parameters and the known quantities. This enables estimation of the unknown parameters even when direct measurements are unavailable, thereby providing a useful method for obtaining crucial information in data‐limited scenarios.

USE OF BORON WASTE IN FLY ASH BASED GEOPOLYMER BRICKS

In study, it is targeted to produce geopolymer bricks by using Eskişehir Kırka region boron waste and Seyitömer thermal power plant waste fly ash. It was aimed to produce geopolymer brick, which is more durable than normal brick physically and mechanically and has thermal insulation properties. Within the scope of the study, the rate of fly ash was kept constant as 10%, and geopolymer bricks were produced by using different ratios (10%, 20%, 30%, 40%, 50% and 60%) of boron waste. In order to determine the physical properties of the produced brick samples, waterloged weight per unit of volume, water absorption (by weight), porosity, heat transmission coefficient of solid objects tests applied. As a result of the study, it was observed that with the increase in the amount of boron waste, waterloged weight per unit of volume, water absorption (by weight), porosity and heat transmission coefficient values of solid objects decreased. It was determined that the compressive strength of the samples increased up to 50% and the boron waste substitution decreased by 60%. It was observed that the flexural strength values were decreased up to 50%, and the boron waste substitution were done. For the determination of its mechanical properties, compressive strength and bending tensile strength tests were of 60% increased. In addition, it was concluded that there is no harm in using boron waste and fly ash substitution at certain rates in the production of bricks, and this situation will have positive effects on the environment and human health.

Comparative dynamics of mixed convection heat transfer under thermal radiation effect with porous medium flow over dual stretched surface

Due to enhanced heat transfer rate, the nanofluid and hybrid nanofluids have significant industrial uses. The principal objective of this exploration is to investigate how thermal radiation influences the velocity and temperature profile. A water-based rotational nanofluid flow with constant angular speed {Omega } is considered for this comparative study. A similarity conversion is applied to change the appearing equations into ODEs. Three different nanoparticles i.e., copper, aluminum, and titanium oxide are used to prepare different nanofluids for comparison. The numerical and graphical outputs are gained by employing the bvp-4c procedure in MATLAB. The results for different constraints are represented through graphs and tables. Higher heat transmission rate and minimized skin friction are noted for triple nanoparticle nanofluid. Skin coefficients in the x-direction and y-direction have reduced by 50% in trihybrid nanofluid by keeping mixed convection levels between the range 3 <upepsilon le 11. The heat transmission coefficient with raising the levels of thermal radiation between 0.5 < {uppi } le 0.9 and Prandlt number 7 < {text{Pr}} le 11 has shown a 60% increase.

Experimental investigation on nano refrigeration using TiO2 CuO and Al2O3 as refrigerants

Volatility of heat flow is vital in the refrigeration and cooling frameworks. However, working fluid was utilized in cooling cycle and they were devouring an Earth-wide temperature boost coefficient at undeniable level, However the an Earth- wide temperature boost up capability of HFC134a is marginally high, it should attested that it is a drawn out elective refrigerants which affect the atmosphere of nation.. By expansion of Nano powders to the outcomes of refrigeration cycle which upgrades in the properties of thermos physical and intensity to improve qualities of the working fluid, accordingly working on the execution of the refrigeration framework. In this work, looking at the impact of utilizing, TiO2,Cuo,Al2O3 - R134a and inorganic oil in the fume pressure framework on the dissipating heat transmission coefficient. Polyester Oil was tried alongside reasonableness what's more, natural accommodating refrigerant R-134a. Results show that TiO2,Cuo,Al2O3 nanoparticles concentralization of 0.8 wt% is ideal and gives most noteworthy intensity move improvement and work on the coefficient of Performance(COP). A test rig of mechanical assembly was fabricate as indicated by the public guidelines of India. Nano TiO2 fixations went from 0.05 to 0.8% volume extent and molecule size from 10 to 70 nm. That's what the outcomes show that evaporator warmth move coefficient increments with the utilization of Nano TiO2,Cuo,Al2O3.Finally it is observed that after mixing the Tio2,Cuo, Al2O3 in HFC134A, there was a drastic decrease in evaporator temperatures at faster rate.

Two-dimensional collisional particle model of the divertor sheath with electron emissive walls

A novel two-dimensional particle-in-cell (PIC) code, named Divertor Edge Simulator of Plasma-wall Interaction with Consistent COllisions (DESPICCO) and developed at CNR-ISTP, is capable of simulating the thin plasma layer of several millimeters, adjacent to the divertor tiles of a Tokamak fusion reactor. Here, kinetic effects and non-neutral plasma physics in the Debye sheath can be self-consistently captured by the PIC approach. The code is firstly benchmarked against literature one-dimensional codes and additional theoretical predictions for a magnetized sheath. Then, it is applied to a realistic divertor scenario featuring an attached plasma with monoblocks (MBs) radial misalignment and gaps, to compute the energy flux amplification factor at the exposed MB edge. A non-ambipolar local current density close to the leading edge and an average sheath heat transmission coefficient larger than the one predicted by classical sheath theory, are found. The effects of electron wall emission and plasma-gas collisions on the ion Mach number and on particle and energy fluxes to the walls are finally estimated to determine future guidelines for simulations. Ion collisions with recycled neutrals and both secondary and thermionic electron emission from the wall are found to have a relevant impact, with the overall effect of reducing by 25% the average ion impact energy, and by 15%–20% the total heavy particles energy flux to the walls, with relevant implications on the divertor wall erosion.

Scaling laws for electron kinetic effects in tokamak scrape-off layer plasmas

Tokamak edge (scrape-off layer (SOL)) plasmas can exhibit non-local transport in the direction parallel to the magnetic field due to steep temperature gradients. This effect along with its consequences has been explored at equilibrium for a range of conditions, from sheath-limited to detached, using the 1D kinetic electron code SOL-KiT, where the electrons are treated kinetically and compared to a self-consistent fluid model. Line-averaged suppression of the kinetic heat flux (compared to Spitzer-Härm) of up to 50% is observed, contrasting with up to 98% enhancement of the sheath heat transmission coefficient, γ e . Simple scaling laws in terms of basic SOL parameters for both effects are presented. By implementing these scalings as corrections to the fluid model, we find good agreement with the kinetic model for target electron temperatures. It is found that the strongest kinetic effects in γ e are observed at low-intermediate collisionalities, and tend to increase (keeping upstream collisionality fixed) at increasing upstream densities and temperatures. On the other hand, the heat flux suppression is found to increase monotonically as upstream collisionality decreases. The conditions simulated encompass collisionalities relevant to current and future tokamaks.

유기단열재 수축에 의한 틈새 발생이 공동주택 외벽의 결로 방지 및 단열 성능에 미치는 영향에 대한 해석 - 열유동(CFD) 해석 및 현장 실측 결과 비교를 중심으로 -

In recent years, due to the strengthening of insulation performance standards and increasing demand for low-energy buildings, the high performance of the insulation material installed in the building is demanded. Meanwhile, crevices due to shrinkage of insulation board may cause thermal bridges and cause a decrease in surface temperature and thermal performance. When the size of the crevices is large, it is difficult to predict only conduction because internal air flow occurs. The purpose of this study is to analyze the heat flow implemented by computational fluid dynamics based on the field measurement and to quantitatively analyze the effect on the crevices by analyzing the effect of the heat flow due to the crevice to lower the surface temperature inside the building wall and the resulting energy loss. After measuring the surface temperature and indoor/outdoor air temperature of the actual wall where condensation occurred in the indoor, the wall was disassembled to check the size of the crevice, and the results of the crevice length and temperature reduction were obtained. Based on this data, the thermal flow analysis is conducted by dividing two cases according to the presence or absence of a crevice connection.BRDue to the occurrence of a crevice of 12 to 15 mm, a surface deterioration of about 9 to 10°C occurred in the upper and lower parts of the wall, and the performance standard of the wall was not met. In addition, as a result of the analysis of the wall, the heat transmission coefficient increased by 1.67 times compared to the existing wall due to the occurrence of crevices.

A Fast Method for Calculating the Impact of Occupancy on Commercial Building Energy Consumption

Occupancy, which refers to the occupant count in this paper, is one of the main factors affecting the energy consumption of commercial buildings. It is important for both building managers and energy simulation engineers to understand how an entire building’s energy consumption varies with different occupancy levels in the process of building automation systems or in assessments of building performance with benchmarking lines. Because commercial buildings usually have large scales, complex layouts and a large number of people, it is a challenge to simulate the relationships between an entire building’s energy consumption and occupancy. This study proposes a fast method for calculating the influence of occupancy on the energy consumption of commercial buildings with different building layouts and existing occupancies. Other occupant behaviors, such as the opening of windows and adjustment of shading devices, are comprehensively reflected in two basic building parameters: the balance point temperature and the total heat transmission coefficient of the building. This new method can be easily used to analyze how building energy varies with occupancy without a physical building’s energy model. An office building in Shanghai is taken as a case study to validate the proposed method. The results show that the coefficient of determination R2 between the calculated value and actual value is 0.86, 0.8 and 0.71 for lighting, cooling and heating energy, respectively, which is suitable in engineering applications.

Convection heat transfer coefficient of building glasses under salt deposition conditions

Glass buildings in coastal regions and islands exposed to the hydrothermal marine environment, in addition to salt deposition and erosion, lead to a change in the surface convective heat transfer coefficient (CHTC) and gradual degradation of the building energy and thermal performance. However, limited research has been conducted on the influence of salt deposition on the CHTC of building glasses. Hence, in this study, the salt deposition characteristics of the glasses were obtained by conducting an accelerated salt spray test. In addition, the influence of salt deposition on the CHTC and heat transmission coefficient (HTC) was investigated. The results indicate that the sizes of the salt spots on the glass surface increased significantly and unevenly. The salt deposition per unit area (p) exhibited a logarithmic growth trend between 14.4 and 40.0 mg/m2, considering the spray time. Under the 10% saline condition, p was larger than that under the 5% saline condition, ranging between 15.6 and 44.3 mg/m2, with an average increase rate of 11.6%. The CHTC exhibited a monotonic increase in terms of the deposition amount on the glass. Compared with the salt-free scenario, the maximum increase in CHTC was 178.7%, which exhibited a linear relationship with p. When p increased to 40.0 mg/m2, the HTC increase rate of the single clear glass and hollow Low-E glass reached 20.1% and 5.2%, respectively. The findings of this study provide insights into the influence of salt deposition on the CHTC of building glasses and can serve as a basis for energy consumption studies in coastal regions.

스마트팜 적용 피복재의 시험을 통한 성능평가 및 냉방부하 분석

The thermal performance database of the covering material which can be used as input data for the smart farm cooling load simulation performance evaluation was analyzed through the test evaluation. Methods: The solar heat gain coefficient of the covering materials (PE, PMMA, PC double layer, woven film) was compared and analyzed through the Korean standard test method and input data was derived. Based on the thermal input data, the cooling load simulation of smart farm was conducted and the simulation performance evaluation of each case was performed to analyze how the indoor cooling load changes by covering materials. Results: The cooling load of the PC double layer was the lowest at 424 W/㎡, and the PE film was the highest at 559 W/㎡. The coefficient of heat transmission was 3.7 W/㎡ ·K~6.7 W/㎡ ·K for each covering materials, and the solar heat gain coefficient was evaluated as 54%~90% visible transmittance was 50%~88%. The cooling load of the PC double layer and PE film showed a difference of 135 W/m2(24%), indicating that the selection of the coating material greatly affects the cooling load. The cooling load was reduced by 25.3% when the cooling setpoint temperature was controlled, and the cooling load was reduced by 35.8% when the internal shading rate was applied by 60%.

Thermohydraulic performance of solar air heater having discrete double arc roughness elements on absorber plate

The creation of a laminar sub region near the absorber wall causes solar air heaters to have limited thermal performance. An experimental analysis indicated that artificial roughness is one of the best strategies for breaking this viscous sub layer and improving absorption efficiency. Artificial roughness stitched on the absorbent plate in manner of discrete double arc roughness elements is generated, generating turbulent flow inside the rectangular duct. The coefficient of heat transmission improves as the roughness element is developed. In the current study, developed a roughness element of the discrete double arc reverse arc manner is used to improve the THP of the solar collector. During testing, relative roughness pitch, p/e = 11.67, relative roughness height, e/ Dh = 0.027, and angle of arc, α = 30°, 45°, 60°, 75°, Reynolds Number, Re = 3000–14000 were utilised as fixed and variable parameters, respectively. After extensive testing, the outcomes have been compared to the above mentioned of a plain absorber plate under the same fluidity circumstances. Experimental investigation revealed that Nusselt number (Nu), and friction factor (f), are 2.59 & 1.96 contrast overhead plain (without roughness element) plates, respectively. At a p/e = 11.67 & α = 60°, overall THP was found to be 2.16.