Superheated Temperature Research Articles

Utilizing OF Thermal Energy OF Gas Turbines Exhaust Gases Working IN Petroleum Sector

The gas turbine stations are used in petroleum sector for different application, such as compressing of gas, pumping of crude oil or water, and power generation. The main parts of these stations are compressor, combustion chamber, and gas turbine. The compressor provides a compressed air for combustion process, and for cooling process of different parts of the station. The fuel (liquid or gas fuel) is injected into the combustion chamber to perform the combustion process. The resulted hot flue gases are passed to the gas turbine to convert its' thermal energy into rotational mechanical energy to operate the air and gas compressors, crude oil or water pumps, and to generate electricity.This work concerns with the applicability of utilizing the thermal energy content in flue gases exit from the gas turbine by adopting a field data received from one of the operating stations in north Oil Company in Iraq. The flue gases mass flow rate, and its' available energy have been calculated. Different operational conditions have been selected to produce superheated steam such as operating pressure range of (0.36-1.4 MPa), with a range of superheated temperature differs than the corresponding saturation temperature by (10-60 oC) for each selected pressure. This work is also concerned with the possibility of producing of hot water for a pressure range of (0.36-1.4 MPa) with a temperature lower than the corresponding saturation temperature by (5 oC). The results show that the power produced reaches (1.4-3.3 MW). Also the hot water produced reaches 90000 kg/hr at operating pressure of 0.36MPa.
 The obtained results in this work are interesting since an elimination of thermal pollution by exhaust gases is accomplished. The available energy in these gases has been utilized to produce either superheated steam or hot water without consuming a conventional fuel.ntroductionI -

Experimental study of heat transfer characteristics of nanofluids nucleate and film boiling on horizontal flat plate

In this paper, the heat transfer characteristics of nanofluids nucleate and film boiling is studied experimentally. For this purpose, Al2O3 and SiO2 deionized water-based nanofluids prepared with three volumetric concentrations of 0.1%, 0.3% and 0.5%. The boiling experiments were conducted on a circular and polished copper surface with a diameter of 25 mm. The results showed that the addition of nanoparticles to the base fluid reduced the heat transfer coefficient of nucleate boiling. The boiling of nanofluids increased the surface wettability and the critical heat flux was significantly higher than that of pure deionized water. The Al2O3 deionized water-based nanofluid with a volumetric concentration of 0.5% had the best performance, with a critical heat flux of 44.56% higher than that of pure deionized water. The presence of nanoparticles in the deionized water-based nanofluid improved the heat transfer coefficient of film boiling. The results showed that the stable film boiling for nanofluids starts at higher wall superheat temperature difference than pure deionized water. Among the investigated concentrations, volumetric concentration of 0.5% had best performance for both nanofluids, so that the minimum heat flux of Al2O3 and SiO2 deionized water-based nanofluids were increased 35.01% and 34.40% compared to pure deionized water, respectively.

Flow Field and Temperature Field in a Four-Strand Tundish Heated by Plasma

Tundish plasma heating is an effective method for achieving steady casting with low superheat and constant temperature. In order to study the flow field, temperature field in tundish heated by plasma, a three-dimensional transient mathematical model was established in the present work. A four-strand T-type tundish in a steelmaking plant was used to explore the changes in the flow field and temperature field of molten steel in the tundish under different plasma heating powers. The results showed that plasma heating affected the flow state of molten steel. It could eliminate the short-circuit flow at outlet. When the plasma heating was 500 kW, the molten steel had an obvious upward flow. The turbulence intensity was improved and distributed evenly with an increase in plasma heating power. In the prototype tundish, the temperature of the outlet was dropped by nearly 2–3 K within 300 s. With the increase of plasma heating power, the low temperature area in the tundish gradually was decreased. When the heating power was 1000 kW, the temperature difference of two outlets was 0.5 K and the overall temperature distribution was more uniform. The research results have a certain guiding significance for the selection of the actual plasma heating power on site.

Experimental Study of Domestic Refrigerator Performance Improvement with Evaporative Condenser

Evaporation of defrosted water in household refrigerators and condenser waste heat utilization has been reported by many researchers but limited literature is available on the study of evaporative cooling in domestic refrigerators (condenser waste heat utilization for defrost water evaporation) with helical coil heat exchangers. This paper is concerned with evaluating domestic refrigerator performance by employing an evaporative helical coil heat exchanger before hot wall condenser which is utilized for evaporation of defrost water and reducing the superheated refrigerant temperature to condensing temperature to reduce the condenser load and improve the overall performance of a domestic refrigerator. Results show that evaporative cooling increases COP of the system by 25.3%, reduces the energy consumption of the refrigerator by 7.3% and the compressor run time by 10.6%. These experimental results also revealed that using two different thermal conductivity tube materials for evaporative helical coil condenser (Copper tube and Zinc coated steel tube) provided with less wall thickness (0.2[Formula: see text]mm) PVC coating results in good agreement for the same evaporation rate of defrosted water.

Improving Energy Efficiency in Supermarkets by Retrofitting Low-E Glass Doors for Open Refrigeration Systems with Digital Semi Hermetic Compressor

This research will be presenting energy efficiency improvement options by retrofitting doors for open refrigeration systems in Central Thailand supermarkets that open during the daytime (06:00 am – 06:00 pm), and are closed during the night-time (00:00 am – 6:00 am). The materials and methods used consisted of 15 open refrigeration cabinets with 82 retrofitted doors supported by 41 frames, with the temperature set at medium. The power consumption was indicated in kW, kWh through a power meter data logger for analysis and summarization. The investment required was €21,694 /store, while the payback period of this research was determined to be at 14 months. The cost of energy savings was found to be within a period of 1.1 years, at the rate of 192,220 kWh/year or €18,503 annually. The retrofitted doors is expected to reduce the cooling load and over-burdening of the compressor. The research found that the most viable solution was to use a digital semi-hermetic compressor that can operate in unload and full load status, that was being controlled by the evaporator temperature (TEV) which was set at -10 degree, the condenser temperature (TCD) set at 38 degrees, and the superheat temperature (TSH) at 10 degrees. In the unload status, the power consumption of the digital semi hermetic compressor will decrease by 50%, which has a significant impact for energy savings and is important for night-time when low cooling load is required whereby the compressor’s multiple start–stop cycles are not required. The investment for a digital semi-hermetic compressor was determined to be €7,800/store, and is able to yield energy savings of up to 26,890 kWh/year, or €2,589 annually, with a payback period of 2.9 years.

Flow boiling heat transfer performance of copper-alumina micro-nanostructured surfaces developed by forced convection electrodeposition technique

The stability and adhesion of developed surfaces to the substrate is directly influenced the boiling performance with respect to the recurring trial runs. For the commercial application point of view, the stability of developed surfaces is an important concern. Therefore, a new multi-step forced convective electrocodeposition technique is proposed for further improvement in adhesion, nucleation sites, wettability, and flow boiling heat transfer. The uniform particles deposition on the surface is achieved by forced convection electrodeposition technique. The SEM images, porosity, wettability, coating thickness, EDS spectrum, and surface roughness are carried out in order to analyze the surface behaviors of the surfaces. The flow boiling tests are conducted on considered surfaces at different mass flow rates with DI water. The maximum variations of 5.3% in critical heat flux (CHF) and 1.3°C in surface temperature are monitored for micro-nanostructured (MS#2) surface between the first and fifth test run. The incipience of boiling (ONB) for MS#2 surface is occurred at surface temperatures of 100.3, 102.1, 103.4, and 106.5°C for the mass fluxes of 53, 113, 268, and 361 kg/m2s, respectively. The maximum augmentation in CHF (~176%) and heat transfer coefficient (~200%) are achieved on MS#2 surface at lower mass flux.Statement of novelty and Significance: The boiling heat transfer mechanism is an efficient heat transfer mode and able to achieve large amount of heat extraction with very small wall superheat temperature from the critical equipments though sensible heat and latent heat of vaporization. In boiling heat transfer process, being a vigorous process, the stability and adhesion of developed surfaces to the substrate is directly influenced the boiling performance with respect to the repetitive test runs. For the commercial application point of view, the stability of developed surfaces is an important concern. Therefore, In the present study, a new four-step (deposition-sintering-deposition sintering) forced convection electrodeposition technique is conceptualized and used in the present work for further improvement in adhesion, nucleation sites, wettability, and boiling heat transfer. The flow boiling tests are conducted on micro/nanostructured surfaces at different mass flow rates with DI water (working fluid). More improvements in CHF and HTC have been monitored with the developed micro- nanostructured Cu-Al2O3 (MS#2) surface.

Bubble Growth in NaCl Solution: Influence of Superheat Temperature and Solution Concentration

An in-depth understanding of vapor bubble growth characteristics is of great importance for the design and optimization of gas–liquid two-phase flow instruments, which are widely utilized in chemical and thermal engineering processes. The effects of dissolved salts on vapor bubble growth remain unclear at present. In this work, we developed a surface-based bubble growth model to analyze the bubble growth rates and interface hydrodynamics in sodium chloride solution by considering the influence of dissolved salt on bubble growth. The effects of the mass fraction of NaCl and the superheat temperature on bubble growth rates and interface parameters were studied. Further, the characteristics of three typical bubble growth stages were discussed, and the roles of interfacial forces under different operating conditions were demonstrated. The results indicate that the bubble growth rates increased with the increase of the superheat temperature and mass fraction. The effects of the superheat temperature on the bubble duration time are more significant than the NaCl concentration. Besides, the validated surface-based bubble growth model could be extended to other electrolytes by modified solution properties and interface evaporation parameters.

Thermodynamic analysis of entropy generation due to energy transfer through circular surfaces under pool boiling condition

Pool boiling is a well-known heat transfer mechanism which is accomplished by submerging a heating surface in a pool of stationary liquid. The role and share of different energy transfer mechanisms in pool boiling can be determined through entropy generation analysis. In this paper, entropy generation due to energy transfer through circular surfaces is analyzed and the optimized thermodynamic system is achieved. Furthermore, two models of total heat flux (linear and nonlinear) are developed for pool boiling heat transfer in which the effect of different parameters such as nucleation site density, contact angle, Prandtl number (Pr) as well as surface diameter are considered. The obtained results reveal the enhanced heat flux and entropy generation as the consequences of increased wall superheat temperature, contact angle, Prandtl number and surface diameter. The developed model is validated by comparing the obtained results with respective experimental data and semi-analytical results. In addition, results exhibit that the maximum entropy generation is observed at $$\Delta T = 15 \,{\text{K}}$$ and $$Pr = 3.5$$ which was equal to 4.06 W m−1 K−1 and 3.78 W m−1 K−1 for Model 1 and Model 2, respectively.

Nucleate and Film Boiling Performance of Ethanol-Based Nanofluids on Horizontal Flat Plate: An Experimental Investigation

In this paper, the heat transfer characteristics of nanofluid nucleate and film boiling are studied experimentally. For this purpose, Al2O3 and SiO2 ethanol-based nanofluids prepared with three volumetric concentrations of 0.1 %, 0.3 %, and 0.5 %. The boiling experiments were conducted on a circular and polished copper surface with a diameter of 25 mm. The results showed that the addition of nanoparticles to the base fluid reduced the heat transfer coefficient of nucleate boiling. The critical heat flux of ethanol-based nanofluids was significantly higher than that of pure ethanol. The Al2O3 ethanol-based nanofluid with a volumetric concentration of 0.5 % had the best performance, with a critical heat flux of 42.36 % higher than that of pure ethanol. The presence of nanoparticles in the ethanol-based nanofluid improved the heat transfer coefficient of film boiling. The results showed that the stable film boiling for nanofluids starts at higher wall superheat temperature difference than pure ethanol. Among the investigated concentrations, volumetric concentration of 0.5 % had the best performance for both nanofluids, so that the minimum heat flux of Al2O3 and SiO2 ethanol-based nanofluids were increased by 45.96 % and 45.67 % compared to pure ethanol, respectively.

Amelioration of pool boiling thermal performance in case of using a new hybrid nanofluid

Unremitting endeavors have been devoted by numerous researchers to ameliorate thermal performance of pool boiling by reducing the superheat temperature value using various approaches. This study aims to experimentally investigate the pool boiling thermal performance of Al2O3 and CeO2 hybrid nanoparticles with 50:50 mixing ratio based deionizedc1 water at atmospheric pressure condition. The pool boiling curves, pool boiling heat transfer coefficient PBHTC enhancement ratio with different dilute volumetric concentrations ranging (0.01–0.1% Vol.) from horizontal typical copper tube were examined. Results demonstrated that the enhancement ratio for hybrid nanofluid was improved compared to DI water, and the higher enhancement ratio was 1.37 for volume concentration of 0.05% Vol at low heat flux. Finally, this type of hybrid nanofluids could remove high heat flux at a small temperature difference, especially with this type of heater geometry, initial surface roughness, nanoparticles type, size, and the volumetric concentration.

Measurement of the onset of nucleate boiling in liquid xenon

We report the first precision measurement of the superheat temperature required for bubble nucleation in liquid xenon of Δ Twall,ONB = (16.9±0.5) K and Δ Twall,ONB = (19.2+0.4−1.1) K at pressures of P = (0.98±0.02) bar and P = (1.32+0.05−0.01) bar, respectively. Both are measured at a subcooled bulk fluid temperature of ∼ 162 K. A dedicated liquid xenon setup is used to measure the temperature at which bubble nucleation first appears on the flat surface of a resistor. The associated average heat flux at the surface of the resistor is determined using fluid dynamics simulations. Future experiments can use these experimental results to determine the likelihood of boiling in liquid xenon and to design effective thermal sinks that prevent bubble nucleation.

Heat balance simulation for evaluating a 315 MW low rank coal-fired power plant performance

The domination of coal-fired power plant as power generation due to its feasibility to ensure a stable supply of electricity to customer. Unfortunately, the use of coal as power plant fuel faces an issue of air pollution. Some efforts have been proposed to make the operated coal-fired power plant meeting the environmental regulations. One of the most potential ways to solve the problem is by improving the coal-fired power plant efficiency and then equate to a greenhouse gas reduction. Thus, heat balance simulation of coal-fired power plant which operates in different conditions have to be studied in order to analyse the power plant performance. In this paper, the heat balance of a 315 MW low rank coal-fired power plant is simulated by Cycle-Tempo. The simulations are carried out for several different operation conditions of the power plant. The Heat Rate will increase of 3.66% when all HPH are on off-duty while it increases by 2.63% when all LPH are on off-duty. Furthermore, the increasing of Superheater temperature of 5 °C will decrease the Heat Rate of 0.59% and it will decrease of 0.39% when the temperature of Reheater increases of 5 °C.

Influence of Deposition and Fouling on Wall Temperature Distribution in Convective Path

Abstract To develop a method of controlling the deposit tube surface temperature, the rules of deposition and fouling on the fireside, and the influence factors of the surface distribution were determined through experiments and theoretical calculations. The surface temperature distribution of a clean tube was compared with that of a deposit tube. Through theoretical calculations, the influence factors of the deposit tube surface temperature were evaluated. Based on the investigation, surface temperature control technology applicable to a super- heater was proposed and the feasibility of this heater was determined. A bimodal distribution was obtained when the temperature distribution of the deposit tube was plotted as a function of the angle, whereas a unimodal distribution was obtained for the clean tube. The results revealed that the heat exchange tube surface temperature is most effectively controlled by controlling the flue gas temperature. Prior to the development of higher performance materials (compared with conventional materials), surface temperature control technology can be used to ensure that the super-heater surface temperature lies below the allowable temperature of existing super-heater materials.

Multi-objective optimization of regenerative ORC system integrated with thermoelectric generators for low-temperature waste heat recovery

Three novel geothermal-based organic Rankine cycle (ORC) systems are proposed to enhance the efficiency and for waste heat recovery purpose. The proposed systems are modeled based on a basic ORC system (concept 1), an ORC system with an internal heat exchanger (concept 2), and a regenerative ORC system (concept 3). Accordingly, two thermoelectric generators (TEG) are introduced into the systems to exploit the waste heat of the system. The condenser is replaced with a TEG unit while the other TEG unit is used to recover the waste heat of the reinjected geothermal fluid. A comprehensive numerical investigation is conducted to compare the proposed systems from the thermodynamic and thermo-economic points of view. Furthermore, the most favorable proposed system is considered for optimization purposes and multi-objective optimization using the genetic algorithm is performed. Accordingly, a Pareto frontier is extracted consisting of the optimal solutions along with the scatter distribution of the critical parameters. The results indicate that the third proposed concept holds the highest exergy and energy efficiency among the studied systems. Also, the concept concludes the highest power output from the employed TEG units. The results further show that the first concept has the lowest associated cost with the system and the smallest payback period and at the same time higher net power generation. At the baseline of the systems, the exergy efficiencies are 59.39%, 57.92%, and 60.27%, and the total product costs are 25.8 $/GJ, 28.79 $/GJ, and 31.27 $/GJ for the first, the second, and the third proposed concepts, respectively. Results of the multi-objective optimization of the third concept reveal that the superheater temperature difference should be kept at higher values while the optimal range of the figure of merit is between 0.9 to 1.6. The proposed systems can be designed practically to exploit the geothermal heat source and recover the waste heat of the system.

Heat transfer study on flowing liquid film of SiO2‐water nanofluid with surfactant confined by metallic foam

SummaryTo solve the urgent issue of rapid heat dissipation in narrow spaces of electronic devices, the nanofluid as coolant is an effective way, in the cases that the thermo‐physical properties and stabilities of coolant solution can be improved by the dispersion of nanoparticles and surfactant in the base fluid, and scattering sodium dodecyl benzene sulphate (SDBS) as the surfactant and SiO2 nanoparticles, respectively, at different concentration ratios into the base fluid of water to form SiO2‐SDBS‐water (SSW) nanofluid in current research. In the liquid film of SSW nanofluid flowing across heating surface confined by porous metal foam, the effects of the concentration ratios of nanoparticles and surfactant on heat transfer and mechanism of heat transfer enhancement are analyzed in gradual heating and rapid cooling. The boiling and cooling performances can be improved in the SSW nanofluids with the proper concentrations of SiO2 nanoparticles as well as matching surfactant, and the deterioration in heat transfer occurs with the mentioned concentrations exceeding the critical values. In the cooling process, the variation of critical heat flux happens with the concentrations of SiO2 nanoparticles and sodium dodecylbenzene sulfonate in the SSW nanofluids, and the concentration ratio of SiO2 nanoparticles to surfactant should be optimized to enhance heat transfer. Specifically at constant SDBS concentration of 50 ppm, and the relative better heat transfer performances can be obtained at SiO2 concentration of ωSiO2 = 100 ppm, in which the removed heat flux increased by 19%, the cooling time shortened from 8.1 to 5.7 seconds and the critical heat flux increased by 18% in comparison with deionized water. The optimized concentration ratio of SiO2 nanoparticles to SDBS to benefit heat transfer changes with variation of SiO2 nanoparticles in nanofluid at the relatively higher superheat temperature.

Experimental investigation of the effect of one-dimensional roughened surface on the pool boiling of nanofluids

The objectives of this research are to develop a special surface for increasing the nucleation heat transfer characteristics, decreasing the superheat temperature and postponing the occurrence of critical heat flux for long term work. A laboratory apparatus was built. In order to more feeding the microlayer of the bubble by capillary force of the micro-grooves, the boiling surface was roughened in one direction. Despite the fact that the boiling characteristics of roughened surface are improved relative to the polished surface, the results are not very impressive Although the boiling of two Nano-fluids, copper oxide and alumina on the micro-groove surface resulted in a significant increase in the nucleation heat transfer but this method cannot be used for a long time process because of the continues deposition of nanoparticles over the time and creation of insulation layer on the micro-groove surface. Therefore, simultaneous utilization of micro- groove surface, as well as the depositing of a thin and porous layer of nanoparticles on the surface increased the feeding of sites and the production of bubbles respectively. The critical heat flux and boiling heat transfer coefficient for the surface deposited with copper oxide nanoparticles enhanced by 46.5 % and up to 74.2% respectively.

Thermodynamic analysis and optimization of a partial evaporating dual-pressure organic rankine cycle system for low-grade heat recovery

The organic Rankine cycle (ORC) has been proven as one of the most effective technologies for low-grade heat recovery. However, its efficiency is limited due to exergy losses caused by the large temperature difference between the heat source and working fluid in the evaporator. To enhance the ORC system efficiency, in this paper, a novel partial evaporating dual-pressure ORC (PEDORC) system is proposed. A mathematical model is developed to evaluate the system thermal characteristics and investigate the effects of key parameters (e.g. evaporating temperature, quality, superheat temperature, energy distribution) on the system performance. Results show that an optimal evaporating temperature in the evaporators exists to achieve the maximum net power output and exergy efficiency. However, the system thermal efficiency increases as the evaporating temperature increases. Furthermore, the best thermal performance occurs when the thermal energy is properly distributed in the evaporators I and II. The performance of the proposed PEDORC system is further compared with the simple ORC (SORC) and basic dual-pressure ORC (BDORC) systems. The results show that the net power output and exergy efficiency of the proposed PEDORC system are increased by up to 27% and 4.6%, respectively, in comparison to the SORC system. By comparing with the BDORC system, the net power output and exergy efficiency of the proposed system are increased by up to 9.2% and 4%, respectively, and the Levelized Cost of Electricity is reduced by up to 4%. These analyses demonstrate that the proposed PEDORC system is an effective means to recover low-grade thermal energy.

The Comparison of Regression Models and Artificial Neural Networks in Predicting Power Generation in a Thermal Coal Power Plant

A significant Eskom’s grid electricity is generated from the thermal coal-fired plants. The study focused on modelling the generated electricity during the “before and after” outage of a typical unit, in one of the Eskom Benson’s thermal coal power plants rated at 600 MW and mechanical conversion efficiency of 35%. The dataset for the chosen input parameters are collected from the metering cards and the generated electrical power are obtained from the installed power meters to the designated unit in the power plant. Multiple linear regression models (MLR) and Artificial Neural Networks (ANN) for both the “before and after outage” power generated are developed, tested and validated with the input parameters as the average air heater temperature, average main stream super-heater temperature, average high pressure heater’s temperature, the total mass of coal burnt, average of the condenser well pressure and temperature and the auxiliary power consumed. The MLR models and the ANNs for both the “before and after” outage power generated gave excellent correlation coefficients of over 0.950. Furthermore, it can be concluded that the ANNs gave better predictions over the counterparts MLRs model based on the correlation coefficients and the mean square errors derived from the models.

Study of a metal hydride based thermal energy storage system using multi-phase heat exchange for the application of concentrated solar power system

Thermal energy storage system is of great significance for the concentrated solar power system to keep the balance between power generation and demand. Metal hydride based thermal energy storage system is regarded as a promising method due to its good reversibility, low cost, and no by-product. Multi-phase heat exchange has much higher heat transfer coefficient than single-phase fluid heat exchange, thus facilitating the steam generation. In this study, a two-dimensional model of the metal hydride reactor using multi-phase heat exchange is proposed to estimate the performance and its feasibility of application in the concentrated solar power system. The results show that the velocity of the heat transfer fluid should match well with the thermal conductivity of the metal hydride bed to maintain the heat flux at a relatively constant value. The match of thermal conductivity of 3 or 5 W/(m·K) and fluid velocity of 0.0050 m/s results in the heat flux up to about 19 kW/m2, which is increased by 3 orders of magnitude than single-phase heat exchange. In the thermal energy storage system, the reheating cycle is recommended to improve the utilization of the thermal energy. The efficiency of the system could be improved from 18.4% to 30.8% using the reheating cycle. The increased efficiency is comparable to the previously reported efficiency of 39.2%. Besides, the operation strategy of raising the steam temperature by increasing the hydrogen pressure or the superheater temperature is suggested for the system to obtain higher efficiency.

Experiments and correlations of saturation boiling of hfe-7000 dielectric liquid on rough inclined copper surfaces

The saturation temperature of only 34 °C at atmospheric pressure, the high boiling figure-of-merit (BFOM), Critical Heat Flux (CHF) and maximum nucleate boiling heat transfer coefficient (hMNB) make HFE-7000 dielectric liquid a good choice for immersion cooling applications. Pool boiling experiments are performed to investigate the effects of inclination angle on saturation boiling of HFE-7000 dielectric liquid on 10 × 10 mm rough copper surfaces. Experiments varied surface average roughness, Ra, from 0.039 to 1.44 µm and inclination angle of the uniformly heated Cu surfaces, θ, from 0o (upward facing) to 180o (downward facing). Captured images of nucleate boiling in various regions of the boiling curve and near CHF using high-speed camera at 1,000 fps help the interpretation of the experimental results. The values of CHF, hMNB, and corresponding surface superheats as well as those of the surface temperature superheat prior to boiling incipience, ΔTexc, are correlated and compared to reported values for other dielectric liquids. The hMNB, which occurs at the end of the fully developed nucleate boiling region, is higher than the heat transfer coefficient at CHF and the corresponding surface superheat is lower. The CHF and hMNB, increase with increasing Ra and/or decreasing θ, while those of the corresponding surface superheats decrease with increasing θ and/or Ra. In the upward facing orientation (θ = 0o), increasing Ra from 0.039 µm (smooth polished) to 1.44 µm increased CHF by ~ 49%, from 20.7 to 30.85 W/cm2, and decreased the corresponding surface superheats by ~ 38.7% from 23.5 to 14.4 K. In this orientation, hMNB increased 250% from 0.88 to 2.2 W/cm2 K, with increased surface roughness from 0.039 to 1.44 mm and the corresponding surface superheat decreased ~ 41.4% form 22.7 K to 13.3K. The values of CHF and hMNB in the downward-facing orientation (θ = 180o) are ~ 27 - 33% and ~40%, respectively, of those in the upward facing orientation (θ = 0o). In the discrete bubbles’ region at low superheats, the nucleate boiling heat transfer coefficient increased, while that in the fully developed nucleate boiling region at high superheats, decreased with increased θ. Developed correlations of CHF, hMNB and the corresponding surface superheats as well as of ΔTexc are in good agreement with present experimental results and those reported for other dielectric liquids. Results confirmed the promising potential of HFE-7000 dielectric liquid for immersion cooling applications.