Peak Heat Flux Research Articles

Mission design for point-to-point passenger transport with reusable launch vehicles

With the progress of SpaceX’s Starship system, a fully reusable launch system appears possible in the near future. With this technological advance, a new class of transport missions could become economically feasible: Rocket-propelled transport of passengers and cargo at near-orbital speeds from one point on the Earth to another. This mission type is investigated for two reference vehicles: Starship from SpaceX and the SpaceLiner concept, developed by DLR-SART. For both vehicles, the properties during reentry are assessed and the impact on the descent trajectory is investigated, including parametric studies with regard to the effect of launch heading and crossrange capability. While the SpaceLiner upper stage relies on its high hypersonic L/D to cover the majority of the distance in quasi-stationary flight within the atmosphere, the Starship relies mostly on a ballistic flight path at higher altitudes. The flight within the upper layers of the atmosphere allows the SpaceLiner to change its heading mid-flight through banking maneuvers and thus efficiently curve around populated areas. However, this prolonged flight at high velocities within the upper atmosphere does necessitate active cooling of the leading edges. An exemplary mission from Shanghai to California is optimized for both reference vehicles, with the optimization target being minimal peak heat loads. Due to the Starship’s reliance on the ballistic portion of its flight to cover range, the peak heat flux is substantially higher on westward missions, compared to the eastward return flight.

Correlation between heat transfer and flow in an internal combustion engine evaluated with a MEMS sensor

Understanding heat transfer is important for developing high-performance internal combustion engines, but heat transfer mechanisms have not yet been elucidated. The objective of this study is to clarify the correlation between flow and heat transfer in an engine. Local instantaneous heat flux and advection speed adjacent to a wall were measured using a resistance-type three-point heat flux sensor to achieve this purpose. Furthermore, local instantaneous Nusselt and Reynolds numbers were calculated based on the measured heat flux and the advection speed using two characteristic lengths: (1) bore diameter and (2) penetration depth. Consequently, it was found that the ensemble-averaged Nusselt numbers varied exponentially as a function of the ensemble-averaged Reynolds numbers in both models, and good correlation equations could be derived. The penetration-depth model reproduced the experimental values more precisely. On the other hand, the Reynolds number index of the bore-diameter model corresponds with the heat transfer on the rear wall of a cylinder installed in a flow. This suggests an analogy between the engine and rear wall of a cylinder. Additionally, the impacts of each heat transfer factor were evaluated. As a result, it was found that a dominant factor until the heat flux peak is the temperature difference between the gas and wall. However, its effect becomes small after the heat flux peak, and it was found that the density and advection speed mainly affect the heat flux decrease.

Accurately predicting hypersonic transitional flow on cone via a symmetry approach

A new algebraic transition model is proposed based on a Structural Ensemble Dynamics (SED) theory of wall turbulence, for accurately predicting the hypersonic flow heat transfer on cone. The model defines the eddy viscosity in terms of a two-dimensional multi-regime distribution of a Stress Length (SL) function, and hence is named as SED-SL. This paper presents clear evidence of precise predictions of transition onset location and peak heat flux of a wide range of hypersonic Transitional Boundary Layers (TrBL) around straight cone at zero incidence, to an unprecedented accuracy as validated by over 70 measurements for varying five crucial influential factors (Mach number, temperature ratio, cone half angle, nose Reynolds number and noise level). The results demonstrate the universality of the postulated multi-regime similarity structure, in characterizing not only the spatial non-uniform distribution of the eddy viscosity in hypersonic TrBL on cone, but also the dependence of the transition onset location on the five influential factors. The latter yields a novel correlation formula for transition center Reynolds number which takes similar functional form as the SL function within the symmetry approach. It is concluded that the SED-SL model simulates TrBL around cone with uniformly high accuracy, and then points out to an optimistic alternative way to construct hypersonic transition model.

SOLPS-ITER simulations of a vapour box design for the linear device Magnum-PSI

A vapour box (VB) is a physical device currently being considered to reduce the high heat and particle fluxes typically impacting the divertor in tokamaks. This system usually consists of a series of boxes that retains neutral particles to increase the amount of collision events with the impacting plasma. The neutral particles come from recycling and recombination of the plasma, gas puffing inside the box and by the evaporation of a liquid metal, typically Li or Sn. Currently, an VB is being constructed for testing in the linear plasma generator Magnum-PSI, operated at DIFFER. Its modular design will allow for open (not enclosing the target) and closed (enclosing the target) configurations, as well as evaporating a liquid metal to create a vapour cloud inside the box. The experiments carried out with this device will investigate its capabilities to reduce the plasma flux towards the target. This work presents a numerical study performed with SOLPS-ITER about the effectiveness of the current VB design in its open configuration to retain neutrals and its effect on the plasma beam properties. This is a first step before validation against experiments and studying closed configurations to ensure that the VB can successfully operate in a wide range of plasma parameters. Simulations show that the VB is capable of retaining neutrals and reducing fluxes to the target without requiring additional gas puffing in High and Low plasma flux scenarios. When lithium is evaporated from inside the box, the hydrogen plasma is completely extinguished and replaced by a low temperature Li plasma with lower flux. The fraction of Li and Li+ transported upstream the VB is three orders of magnitude below the amount evaporated form the central box, as most of the lithium is condensed in the side boxes and another small portion (two orders of magnitude below the amount evaporated) is deposited on the target. The VB design in its open configuration can mitigate incoming plasma peak heat flux by , which represents a fraction of and for the High and Low flux scenarios. This effect is expected to be higher when a closed configuration is employed, which could result in a significant reduction of heat fluxes on the divertor of tokamaks once that this design is extrapolated to the toroidal geometry, with just a minimal amount of Li and Li+ reaching the core.

Argon–seeded detachment during ELM control by RMPs in KSTAR

In this study, we demonstrate argon-seeded discharges that exhibited a detached divertor during the full suppression and mitigation of edge-localized modes (ELMs) by an International Thermonuclear Experimental Reactor-like, three-row resonant magnetic perturbation (RMP) configuration in KSTAR. During the ELM suppression phase, the peak heat flux on the divertor target was successfully reduced from 1.6 MW m−2–0.5 MW m−2 via argon seeding. Further, the ion saturation current densities corresponding to the particle fluxes on both targets were reduced by more than 50%. During the RMP grassy-ELM regime, a further reduction to 0.1 MW m−2 in the divertor heat load was successfully achieved. A highly localized radiation zone near the X-point was also observed during divertor detachment. The calculated degree of detachment based on the two-point model increased to levels of approximately 3 and 2.3 for the outer target and inner target cases, respectively. These results provide valuable information regarding the effect of mid-Z impurities on RMP-detachment-compatible discharges.

Hot Spot Cause Analysis and Shaping Optimization Design of the Monoblock Divertor Target Plate in EAST

The monoblock divertor target plate (MDTP) is a mainstream divertor target plate. MDTP was installed in EAST and in WEST and will be used in ITER. Local high-temperature hot spots (HS) were observed on MDTP during a plasma experiment. HS will reduce the lifetime of MDTP. In this paper, the causes of HS on MDTP are determined through theoretical analysis and are verified by numerical simulations. The HS on MDTP seem to be caused by small high-density heat load areas on the toroidal and poloidal direction surfaces facing the incident direction of the plasma strike line (PSL) of the MDTP tungsten block. When toroidal HS and poloidal HS appear simultaneously, a super local high-temperature HS will be formed at the corner (facing the incident direction of PSL) of the MDTP tungsten block. The HS on MDTP can be eliminated by optimizing the geometry of the MDTP tungsten block, when the plasma configuration is determined. A method and the scope of application of the method, which can be used for tungsten block geometry optimization, are given in this paper. In order to facilitate the selection of a divertor configuration, the heat flux–carrying performance of the optimized MDTP was evaluated. In order to attain a maximum temperature within MDTP of less than 900 K, it was found that if the poloidal incidence angle between PSL and MDTP can be stably controlled as 5 deg (or 35 deg), MDTP can directly withstand PSL with a peak heat flux density of no more than 90 (or 40 ).

Multi-physics coupled simulation on steady-state and transients of heat pipe cooled reactor system

With superior inherent safety and low maintenance demand, heat pipe cooled micro-reactor is a potential solution for decentralized remote electricity supply, as well as space power technology. Multi-physics coupled analysis is important to evaluate the inherent safety feature of micro-reactor. However, in the existing multi-physics coupling simulations, lumped parameter core heat transfer model and low-fidelity heat pipe model cannot accurately predict steady-state and transient safety margin of the reactor. In order to improve the simulation accuracy, a standalone two-dimensional transient high-temperature heat pipe analysis code was developed and validated. The heat pipe analysis code was coupled with the three-dimensional thermal conduction calculation of reactor core, as well as the point reactor kinetics, the alkali metal thermal-to-electric converter model and the heat pipe radiator model, to realize fully coupled analysis of reactor system. With the power distribution in the reactor core, the steady state, startup transient and single heat pipe failure accident were simulated based on the multi-physics coupling. The steady-state simulation results show that the heat flux of heat pipes shows significant non-uniformity in both circumferential and axial directions. The peak heat flux (120 kW/m2), with the twice value of averaged one (60 kW/m2), occurs on the heat pipes near the reactor edge rather than in the center. During reactor startup, the reactivity-insertion rate of 1.67e-3 $/s increases the transient peak heat flux to 260 kW/m2. The isothermal feature of heat pipes results in inverse heat transfer, i.e. from heat pipes to reactor structure, which improves the axial and radial reactor heat transfer and flattens the reactor temperature distribution. In the central heat pipe failure accident, more severe local temperature rise was observed in the core structure than that in the fuel pins. The peak heat flux location is shifted to the heat pipes adjacent to the failed heat pipe. Benefitted from the developed high-fidelity multi-physics coupling approach, the realistic transient phenomena in heat pipe cooled micro-reactor could be revealed.

Influence of upstream wall slope on aerodynamic properties of a rectangular cavity in rarefied hypersonic flows

A comprehensive numerical study is performed to reveal influence of the upstream wall slope on aerodynamic properties as rarefied hypersonic flows pass through the two- and three-dimensional cavity configurations using the direct simulation Monte Carlo (DSMC) method. In this work, slope effect is obtained by the cavity upstream wall sloping upward and downward as well as bulging partially. Besides, cases of freestream with different velocities and altitudes are taken into account to examine the slope effect. It is found that cavity flow is transformed from the open type to the transitional and finally to the closed as the cavity upstream wall gradually slopes upward, promoting the heat energy exchange between gas molecules with the cavity floor, and meanwhile achieving a considerable rate of decrease of the peak heat flux on the reattachment corner. However, the upstream wall sloping downward or bulging partially seems to only have a slight effect on cavity flow and wall heat flux. It's worth noting that slope effect is closely related to velocity and altitude of the freestream, such as the greater the velocity and altitude, the stronger the slope effect. For the three-dimensional cavity configuration, influence of the upstream wall slope on cavity flow and wall heat flux is weaken considerably due to the three-dimensional effect. From the perspective of optimal design for the hypersonic thermal protection system, the cavity with an upward upstream wall is proposed because it not only reduces peak heat flux on the reattachment corner, but also decreases gas temperature inside the cavity.

Influence of Non-Uniform Bluntness on Aerodynamic Performance and Aerothermal Characteristics of Waverider

The waverider is widely used in hypersonic vehicles with its high aerodynamic performance, but due to the serious aerothermal environment, its sharp leading edge should be blunted. Circular blunt is one of the commonly used aerothermal characteristic protection methods. Circular blunt with larger diameter can reduce peak heat flux, but at the same time, it will lead to larger drag. The existing research shows that under the same blunt diameter in two-dimensions, the non-uniform blunt can reduce the peak heat flux by 20%, and the difference of drag is small. In this paper, the non-uniform blunt profile is applied to the three-dimensional waverider, and the influence of the non-uniform blunt profile on the aerothermal characteristic performance and aerodynamic performance of the waverider is studied, and the results are compared with those of circular blunt. The numerical simulation is used to compare and analyze the waverider under different angles of attack, flight altitudes, and Mach number. The results show that the peak heat flux of the waverider with non-uniform blunt reduces by about 17% compared with that with circular blunt under a small angle of attack range, Mach 2-10, and a flight altitude of 15–35 km. Meanwhile, when the blunt height/diameter is 20 mm, the aerodynamic performance difference between the two different blunt profiles does not exceed 3% within a 15 degrees angle of attack, Mach 2-10, and flight altitude of 15–35 km. The non-uniform blunt profile can be applied to the design of the three-dimensional waverider.

On aerodynamic characteristics of rarefied hypersonic flows over variable eccentricity elliptical cavities

A comprehensive numerical study is performed to reveal the pressure on and heat flux to elliptical cavity surfaces using the direct simulation Monte Carlo method with the influences of elliptical cavity eccentricity, freestream altitude, freestream Mach number, and upstream wall curvature analyzed in detail. The obtained results show that both the high-pressure and high heat flux areas are located around the top lip of the downstream sidewall of an elliptical cavity, and whose peak pressure and peak heat flux are usually tens of times larger than those on the cavity floor; the depth of the high-pressure and high heat flux areas moving to the cavity floor is determined by the half axis length in streamwise, while the width of the two areas is controlled by that in spanwise. Compared with the cylindrical cavity, the elliptical cavity has slightly smaller peak pressure and peak heat flux on the downstream sidewall but has much smaller values on the cavity floor. For two elliptical cavities with the same eccentricity, the one that has a shorter length in streamwise is overall better in reducing the surface pressure and heat flux. The freestream altitude and Mach number also play an important role in affecting the surface pressure and heat flux. In comparison with the horizontal upstream wall, the convex upstream wall reduces the peak pressure and peak heat flux on the downstream sidewall but greatly raises them on the cavity floor, and the concave upstream wall makes them drop sharply in the form of a cliff no matter on the downstream sidewall or on the cavity floor. The physical mechanism behind the wall curvature effect can be explained as follows: surface pressure and heat flux on the downstream sidewall are originated from the violent impact of the external high-speed airstream on the sidewall, while those on the cavity floor are derived from the friction between the rotating vortices inside the cavity and the cavity floor.

Power exhaust and core-divertor compatibility of the baffled snowflake divertor in TCV

A baffled snowflake minus low-field side (SF-LFS) is geometrically-optimised in tokamak à configuration variable, increasing divertor neutral pressure, to evaluate the roles of divertor closure (comparing with an unbaffled SF-LFS) and magnetic geometry (comparing with a baffled single null (SN)) in power exhaust and core-divertor compatibility. Ohmically-heated L-mode discharges in deuterium, with a line-averaged core density of approximately m−3, are seeded with nitrogen to approach detached conditions. Baffles in the SF-LFS configuration are found to reduce the peak outer target heat flux by up to , without significantly affecting the location of the inter-null radiation region or the core-divertor compatibility. When compared to the baffled SN, the baffled SF-LFS exhibits a reduction in the outer target heat flux by up to and the ability to balance the strike-point distribution of heat flux. These benefits are less significant with N2 seeding, with similar peak target quantities (such as heat flux, electron temperature and ion flux) and divertor radiated power. Despite a radiating region located farther from the confined plasma for the SF-LFS than the baffled SN, no change in core confinement is observed. Core effective charge even indicates an increase in core impurity penetration for the SF-LFS. These experiments constitute a good reference for detailed model validations and extrapolations, exploring important physics such as core impurity shielding and the dependence of divertor cross-field transport on magnetic geometry.

Realization of thousand-second improved confinement plasma with Super I-mode in Tokamak EAST

Mastering nuclear fusion, which is an abundant, safe, and environmentally competitive energy, is a great challenge for humanity. Tokamak represents one of the most promising paths toward controlled fusion. Obtaining a high-performance, steady-state, and long-pulse plasma regime remains a critical issue. Recently, a big breakthrough in steady-state operation was made on the Experimental Advanced Superconducting Tokamak (EAST). A steady-state plasma with a world-record pulse length of 1056 s was obtained, where the density and the divertor peak heat flux were well controlled, with no core impurity accumulation, and a new high-confinement and self-organizing regime (Super I-mode=I-mode+e-ITB) was discovered and demonstrated. These achievements contribute to the integration of fusion plasma technology and physics, which is essential to operate next-step devices.

Study on hypersonic drag and heat reduction of a spiked blunt body with multiple flat aerodisks and rear opposing jets

The performance of a proposed drag and heat reduction scheme that combines multiple flat aerodisks and the rear opposing jet is numerically investigated using compressible Reynolds Averaged Navier-Stokes (RANS) equations coupled with the shear stress transport (SST) turbulence model. Results show that the introduction of the multiple flat aerodisks and the rear opposing jet push the reattachment shock wave away from the blunt body and reduce the intensity of reattachment shock wave as well. Compared with the configuration with only a spike and a conical aerodisk, the present configuration shows a reduction in peak pressure and peak heat flux of the blunt body surface by 70.21% and 84.84%, respectively. Furthermore, the impact of configuration parameters (i.e., jet pressure ratio, spike length, aerodisks diameter, number, and position) on the flow field, drag and heat reduction performance are also investigated. The results reveal that increasing the jet pressure ratio can enhance the performance of drag and heat reduction. Increasing the length of the spike can get a better drag reduction performance. Increasing the diameter of flat aerodisk Ⅲ significantly enhances the compression of hypersonic free stream to reduce the intensity of reattachment shock wave. The configuration with four flat aerodisks has better drag and heat reduction performance. Compared with the baseline configuration, the maximum reduction of peak pressure and peak heat load of the blunt body surface can be achieved by moving the flat aerodisk Ⅱ forward.

Peak heat flux prediction of hypersonic flow over compression ramp under vibrationally excited free-stream condition

In hypersonic shock tunnel experiments, the high-temperature reservoir gas expands and accelerates so rapidly that there is not enough time for vibrational energy relaxation. As a result, thermal nonequilibrium gas flow is frequently encountered in the test section, and this significantly affects the measured heat flux. In this paper, hypersonic compression-ramp flows are studied numerically to investigate the effect of incomplete vibrational energy accommodation on the separation flow structure and peak heat flux in the reattachment region under low-to-medium Reynolds number and high Mach number conditions. Numerical results and theoretical analysis suggest that the vibrational energy accommodation has no noticeable impact on the length scale of the separation zone, but strongly influences the peak heat flux of the separated ramp flows. Decomposing the peak heat flux into translational–rotational energy and vibrational energy components, qtr and qv, respectively, we find that qv/qtr characterizes the nonequilibrium degree of the vibrational energy accommodation. A formula for predicting the peak heat flux is then proposed, taking the effect of incomplete vibrational energy accommodation into consideration. Finally, surface heat flux measurements in a hypersonic shock tunnel indicate that a deviation of up to 13% in total peak heat flux could arise if vibrational energy accommodation is not considered under the vibrationally excited free-stream condition.

AEROTHERMODYNAMICS OF COMBINED SPIKE AND COUNTERFLOW JET TECHNIQUE FOR REACTING HYPERSONIC FLOWS

Computational investigation is carried out to estimate the drag force and surface heating load for hypersonic reacting flows. An in-house viscous nonequilibrium finite volume-based reacting gas solver has been utilized. This solver is capable of investigating 11 chemical elementary reactions and temperature-dependent specific properties to reveal the effect of lower as well as higher freestream stagnation enthalpy conditions. Initially, the calorically perfect-gas and real-gas model-based simulations are carried out to understand the real-gas effects in the presence of a metallic spike. Computed surface pressure and heat flux are compared for the freestream stagnation enthalpy of 2 MJ/kg. The real-gas model predicts a 5% higher drag and 57.21 kW/m<sup>2</sup> higher peak heat flux compared to the perfect-gas model. However, lower enthalpy conditions predict almost the same drag force for any spike length. Further, a counterflowing jet is installed at the root of the spike, and flow field alterations are studied for this proposed integrated configuration. The root jet further pushes the conical shock in the upstream direction and provides an extra-large recirculation zone. Here, the possibility of drag and surface heat flux reduction is very much evident due to the decrease in surface pressure and presence of low-temperature jet gas in the vicinity of the object. Various freestream stagnation enthalpies, as well as the jet pressures, are considered to investigate the performance alterations by the combination technique. It is observed that the drag and surface heat load reduction efficiency of the combined configuration decreases with an increase in the freestream stagnation enthalpy. Moreover, it increases when increasing the root jet pressure for given enthalpy conditions. Hence, instead of attaching a long spike at the stagnation region of a blunt-shaped object, the use of a short spike and low-pressure root jet is recommended for a better reduction in drag and surface heat load.

Thermal Protection Mechanism of a Novel Adjustable Non-Ablative Thermal Protection System for Hypersonic Vehicles

In order to improve the thermal protection performance of the active thermal protection system (TPS) based on the spike and jet, an adjustable non-ablative thermal protection system, of which the spike can be rotated in the direction of the free stream, is proposed in this paper. The thermal protection mechanism and the optimal installation angle are analyzed by adopting the numerical method. The results show that the angle of attack has great influence on the peak heat flux of hypersonic vehicles, the dangerous point is on the windward side of the vehicles at the non-zero angle of attack. With the increase in angle of attack, the heat flux of the windward side of the vehicles rises rapidly, leading to the decrease in the global thermal protection efficiency. The adjustable non-ablative TPS in this paper greatly reduces the aeroheating of the windward side through the installation angle between the spike and nose cone, thus improving the global thermal protection efficiency. The optimal installation angle can be obtained by numerical or experimental methods in engineering design, and the difference between the angle of attack and the optimal installation angle is about 2.4° for the proposed model. Therefore, the installation angle can be automatically adjusted based on the angle of attack to achieve the highest thermal protection efficiency.

Investigating the rocket base flow characteristics and thermal environment of different nozzle configurations considering afterburning

During launch vehicle ascent, the base flow regimes of multi-nozzle rockets become increasingly complex owing to plume interactions. We developed a numerical method using the hybrid RANS/LES approach and the discrete ordinate method to accurately estimate the base thermal environment. Moreover, the finite-rate chemical kinetics are employed to calculate afterburning reactions. The validity of the numerical method is established by achieving a good agreement between the numerical results and wind tunnel data. Subsequently, the reacting and non-reacting flows of the three types of nozzle configurations were simulated at six different altitudes. The numerical results reveal that the plume interactions become stronger with the increase in flight height and total number of nozzles, and the maximum Cp of the four-nozzle rocket was 34.75% and 56.52% higher than that for three- and two-nozzle rocket at 40 km, respectively. After considering the afterburning effect, the maximum temperatures of the two-, three-, and four-nozzle rockets increased by 10.16%, 7.69%, and 5.43%, respectively, owing to the difference in plume collisions. With increasing altitude, the rocket base heating rate distribution changed significantly. The peak heat flux of the rocket base initially increases before decreasing with the maximum value of 147.32 kW/m2, 872.75 kW/m2, and 1395.80 kW/m2 for two-, three-, and four-nozzle rockets, respectively.

A High-Order Hybrid Numerical Scheme for Hypersonic Flow Over A Blunt Body

A hybrid scheme is developed for direct numerical simulations of hypersonic flows over a blunt body. The scheme switches to the first-order AUSMPW+ scheme near the bow shock to provide sufficient dissipation to handle the carbuncle phenomenon. In the smooth part of the computational domain, a sixth-order central scheme with an eighth-order low-pass filter is adopted to provide high spatial accuracy to resolve turbulence. The hybrid scheme is shown to be able to obtain smooth and accurate predictions of laminar hypersonic flows over a blunt body. Using the hybrid scheme, a direct numerical simulation of a Mach 6 hypersonic flow over a circular cylinder is conducted. The result shows the turbulent structures in the near-wall region are well resolved by the hybrid scheme, and the bow shock is also captured without introducing any numerical oscillations. With the boundary layer transition on the cylinder’s surface, the simulation indicates that the heat flux peak shifts from the stagnation point to the transitional zone and its peak value is increased by 50\(\%\).

Improved heat and particle flux mitigation in high core confinement, baffled, alternative divertor configurations in the TCV tokamak

Nitrogen seeded detachment has been achieved in the tokamak a configuration variable (TCV) in alternative divertor configurations (ADCs), namely X-divertor and X-point target, with and without baffles in H-mode plasmas with high core confinement. Both ADCs show a remarkable reduction in the inter-ELM particle and heat fluxes to the target compared to the standard divertor configuration. 95%–98% of the inter-ELM peak heat flux to the target is mitigated as a synergetic effect of ADCs, baffling, and nitrogen seeded detachment. The effect of divertor geometry and baffles on core-divertor compatibility is investigated in detail. The power balance in these experiments is also investigated to explore the physics behind the observed reduction in heat fluxes in the ADCs.

Thermal performance analysis of a passive hybrid earth-to-air heat exchanger for cooling rooms at Mexican desert climate

This research incorporates two passive technologies selected to offer thermal comfort conditions in a room exposed to extreme desert climatic conditions (Hermosillo, Sonora, Mexico). On the one hand, a rectangular earth-air heat exchanger assisted with PCM (REAHE + PCM) is implemented. Its job is to supply cooled air to the room at temperatures below the comfort temperature. On the other hand, a room with PCM on its ceiling (room + PCM) is proposed, to reduce the thermal load towards the room and shift the thermal peak load, acting as thermal insulation. Hoping that the benefits of this combination of passive technologies provide the thermal comfort conditions required in a building in this region and thereby eliminate or reduce the consumption of electrical energy in conventional refrigeration systems. This article reports a detailed transient study of the thermal behavior of a passively cooled room. The effect of position, thickness, latent heat, and phase change temperature of the PCM in the room was investigated. Also, the different room configurations reported the time evolution of heat fluxes, temperatures, coefficient of performance (COP), and liquid fraction. A comparison between the proposed system and a room without PCM was made. Adding PCM to the roof can drop the peak heat flux in the ceiling by up to 33%. It was found that the most favorable system was with the PCM placed on the top of the room with a thickness between 1.5 cm and 2.0 cm. The best configuration kept an average room temperature of 0.6 K below the comfort temperature. The maximum temperature in the room only exceeded the comfort temperature by 0.33 K. The average COP varied between 264 and 288 for the room systems, while the average COP for the REAHE-PCM was 307. This combination of technologies is satisfactory for the climatic conditions studied.