Outlet Air Research Articles

Exploring forced convective solar drying of henna (Lawsonia inermis) and its effect on the biological activities: Comparison with open sun dried product

The first focus of this study is to investigate the design and behavior of locally built solar dryer during processing henna leaves. This was performed through the determination of the most important parameters that effect drying process. Appropriately, it was found that solar radiation has a direct effect on the collector outlet air temperature and consequently the product moisture content. Accordingly, high radiations lead having high air temperature at the drying chamber and consequently, the moisture content will decrease rapidly. Similarly, lower radiations will still lead to decrease of the moisture content, however, the drying rate will be less important than at high radiations. On the other hand, air velocity has an inverse dissipative effect of the energy and its increase leads to the decrease of the outlet temperature of the solar collector. Indeed, the highest outlet temperature from the solar collector was around 32 °C at an air velocity of 2 m/s. At 5.5 m/s, this temperature dropped to around 27 °C. The second objective of this study is to present the effect of different drying methods (i.e. forced convective solar drying and open sun drying) of Lawsonia inermis on the content of secondary metabolites (phenolic and flavonoid compounds) and compare the results with fresh henna samples. The yield of phenolic compounds was determined, and the dry crude extracts were found to be richer than the fresh sample in all of the drying modes used. The best yields are obtained with convective solar dryer and open sun drying samples (28.6 and 13.93%), respectively. The total phenolic and flavonoid contents of convective solar dryer product were 25 and 10% higher than open sun dried samples. Antioxidant tests (DPPH, ABTS, and ferric reducing power) revealed the scavenging and reducing abilities of the extract dried with the solar dryer. The values of antioxidant capacities measured by the three different methods were all consistent, appropriate, and highly correlative for assessing total antioxidant capacities. The solar dryer allows the preservation or even the increase of the antioxidant activity of the tested extracts.

Longitudinal viral shedding and antibody response characteristics of men with acute infection of monkeypox virus: a prospective cohort study.

Understanding of infection dynamics is important for public health measures against monkeypox virus (MPXV) infection. Herein, samples from multiple body sites and environmental fomites of 77 acute MPXV infections (HIV co-infection: N = 42) were collected every two to three days and used for detection of MPXV DNA, surface protein specific antibodies and neutralizing titers. Skin lesions show 100% positivity rate of MPXV DNA, followed by rectum (88.16%), saliva (83.78%) and oropharynx (78.95%). Positivity rate of oropharynx decreases rapidly after 7 days post symptom onset (d.p.o), while the rectum and saliva maintain a positivity rate similar to skin lesions. Viral dynamics are similar among skin lesions, saliva and oropharynx, with a peak at about 6 d.p.o. In contrast, viral levels in the rectum peak at the beginning of symptom onset and decrease rapidly thereafter. 52.66% of environmental fomite swabs are positive for MPXV DNA, with highest positivity rate (69.89%) from air-conditioning air outlets. High seropositivity against A29L (100%) and H3L (94.74%) are detected, while a correlation between IgG endpoint titers and neutralizing titers is only found for A29L. Most indexes are similar between HIV and Non-HIV participants, while HIV and rectitis are associated with higher viral loads in rectum.

Examination of smart battery thermal management system using the counter flow of air and nanofluid for cooling cylindrical rechargeable batteries for better resilience

This paper examines smart thermal management of a battery pack (BTK) with a square arrangement of 16 cylindrical battery cells numerically. The cooling of the battery is carried out simultaneously using laminar airflow in a channel and laminar nanofluids (NFs) flow in the tube inserted between the battery cells. The BTK includes rechargeable lithium-ion cells and a tube placed in the channel. The inlets of air and NFs are counter-flow, and the study is done at constant air velocity for different NFs velocities in the tube from 0.001 to 0.003 m/s and different volume percentages (VOP) of NFs from 1 % to 3 %. The numerical study is performed transiently using the finite element method in 2000 s. The results demonstrate that the use of NFs and air for the thermal management (THMT) of battery cells results in better temperature uniformity on the battery cells, especially in the rows placed at the outlet. An increment iimproveP of nanoparticles improves the heat transfer coefficient (HTRC) between air and NFs flows. Also, enhancing the VOP of NFs increases the temperature of the outlet air and decreases the temperature of the outlet NFs. The average temperature (T-Av) and the maximum temperature (T-Mx) of the BTK are high until the battery is charged. They are reduced when the battery charge is stopped due to the air and NFs flows.

Ventilation improvement for effective protection of healthcare workers in negative pressure airborne infectious isolation room from viral aerosols

A negative pressure airborne infectious isolation room (AIIR) is the primary healthcare air contamination control system used for the treatment of severe respiratory infectious patients. Effects of the ventilation system configuration and conditions on airflow pattern, aerosol distribution and ventilation performance were investigated using computational fluid dynamics (CFD). The field measurement by SARS-CoV-2 environmental surface test was also conducted. The cycle threshold values from transcription polymerase chain reaction (RT-PCR) method showed inverse relation to the simulated number of particles trapped on the surfaces indicating a good agreement. Modification of the present AIIR to have alignment between air inlet and outlet where the aspect ratio of the air outlet, Width (W): Height (H) = 1:1 (Improved case: IC#1) showed a 78 % reduction of aerosol concentration in healthcare workers (HCWs) zones. Aerosol concentrations were increased when the openings of the air outlet were enlarged. Addition of air outlet led to large swirling air, resulting in more aerosols being trapped and suspended in the air. Results suggested that AIIR with alignment air inlet on the ceiling and air outlet at the wall over the patient's head with W:H = 1:1 be the most suitable configuration to maximize the ventilation performance and minimize exposure risk to aerosolized viral infection for HCWs. Air change rate plays a more important role than the differential pressure on the removal efficiency. The differential pressure value should be at least −2.5 Pa and the air supply rate 12 ACH for effective protection of HCWs in the negative pressure AIIR.

Experimental evaluation of a heat exchanger for different configurations between internal and external flow

In the present work, the determination of the thermal effectiveness and temperature of the air at the outlet of a scale prototype of a heat exchanger immersed in flowing water was developed experimentally. This depended on the position of the working fluid (air) and of the heat exchanger positioning configuration. The tested positions were parallel flow, quasi-parallel oblique, counterflow, quasi-counterflow oblique, and crossflow. The temperature of the air at the outlet of the heat exchanger and the thermal effectiveness are essential to determine the most convenient operating position of these systems, especially those related to shallow geothermal energy. The thermohydraulic aspects of the heat exchanger presented were evaluated, by the Number of Transfer Units-Effectiveness (NTU-ε) method, under conditions of water flow in a natural channel and air flow induced by a blower, the system was built from commercial copper pipe and temperature sensors were placed in both the exchanger and the water to record temperature changes. The results of this study indicate that when the exchanger is positioned in the oblique quasi-counterflow position and the oblique quasi-parallel position, it exhibits the lowest air outlet temperatures and highest thermal effectiveness, which is relevant for building cooling applications.

Improving the sustainability and effectiveness of photovoltaic evaporative cooling greenhouse in the Sahel

Anthropogenic climate change has caused worldwide extreme weather events including droughts, floods and heatwaves. It disproportionately affects developing countries through food insecurity. Greenhouse is important and relevant to the food-energy-water security in many regions. This study investigates the thermal behavior of photovoltaic evaporative cooling greenhouse made with eco-friendly coolers. The cooling potential of local plant materials was assessed under ambient conditions. Experimental thermal data obtained from optimized evaporative cooling system equipped with Hyphaene thebaica fibers (HF-pad) and conventional Celdek pad (C-pad), were used in heat and mass transfer equations to derive the greenhouse cooling performances. Computational fluid dynamics analysis software was used to investigate the refrigerant fluid distribution in the greenhouse. Cooler using HF-pad allows to keep the microclimate below 25 °C, with maximum moisture rate up to 80%, under harsh ambient conditions (temperature: 30–45 °C, humidity: 10–15%). HF-pad had the highest cooling coefficient of performance (COP = 9 against 6 for C-pad), the best cost to efficiency ratio (CER = 5; 4 times less than C-pad) and the lowest outlet temperature (20.0 °C). Due to higher outlet air velocity (1.116 m/s against 0.825 m/s for HF-pad), C-pad cooler spread cool air (20.5 °C) up to 1.25 m farther than its counterpart, creating higher pressure in the atmosphere (1.42 Pa against 0.71 Pa), with 2 times turbulent kinetic energy (0.014 J/kg). HF-pad presented cooling performances that compete with conventional pads. Moreover, optimization of HF-pad frame engineering and the technology scaling up to industrial level can allow better thermal and economic performances.

Incineration-source fingerprints and emission spectrums of dioxins with diagnostic application

Despite increasing waste-to-energy (WtE) capacities, there remain deficiencies in comprehension of 136 kinds of tetra- through octa-chlorinated dibenzo-p-dioxin and dibenzofurans (136 PCDD/Fs) originating from incineration sources. Samples from twenty typical WtE plants, encompassing coal-fired power plants (CPP), grate incinerators (GI), fluidized bed incinerators (FBI), and rotary kilns (RK), yielded extensive PCDD/F datasets. Research was conducted on fingerprint mapping, formation pathways, emission profiles, and diagnostic analysis of PCDD/Fs in WtE plants. Fingerprints revealed a prevalence of TCDF, followed by PeCDF, while CPP and RK respectively generated more PCDD and HxCDD. De novo synthesis was the predominant formation pathway except one plant, where CP-route dominated. DD/DF chlorination also facilitated PCDD/F formation, showing general trends of FBI > GI > CPP > RK. The PCDD/F emission intensities emitted in air pollution control system inlet (APCSI) and outlet (APCSO) followed the statistical sequence of RK > FBI > GI > CPP, with the average I-TEQ concentrations in APCSO reaching 0.18, 0.08, 0.11, and 0.04 ng I-TEQ·Nm−3. Emission spectrum were accordingly formed. Four clusters were segmented for diagnosis analysis, where PCDD/Fs in GI and FBI were similar, grouped as a single cluster. PCDD/Fs in CPP and RK demonstrated distinctive features in TCDD, HxCDD, and HxCDF. The WtE plants exceeding the limit value tended to generate and retain fewer TCDD and TCDF yet had higher fractions of HxCDD and HxCDF. The failure of APCS coupled with the intrinsic source strength of PCDD/Fs directly led to exceedance, highlighting safe operational practices. This study motivated source tracing and precise evaluation of 136 PCDD/Fs based on the revealed fingerprint profiles for WtE processes.

Development and experimental study of a small-scale adsorption cold storage prototype with stable and tunable output for off-grid cooling

Comfort cooling is a growing demand in summer outdoor activities and work. Adsorption cold storage (ACS) can achieve long-term cold storage without insulation measures and release cold without requiring electricity input. However, the challenges, including unstable cooling output and huge volume, hinder its wide applications. In this study, a small-scale silica gel-water ACS prototype for off-grid cooling is developed and experimentally investigated under typical summer conditions. The heat pipe structure is employed in the adsorption bed for heat transfer enhancement and volume reduction. Valve opening control is utilized for cooling output stabilization and adjustment. The experimental results show that the prototype achieves 6.36 h of cooling output with the outlet air temperature of 25 °C and the average cooling power of 107.67 W under the environment conditions of 35 °C and 40 % RH, indicating an effective cold storage capacity of 685 Wh and an operating efficiency of 0.30. Furthermore, the stable output air temperature can be flexibly adjusted from 19 °C to 27 °C while maintaining the inlet air temperature at 35 °C during the discharging process. Notably, the charging environment temperature shows a minimal influence on the cooling output performance. The prototype's design is novel and applicable for portable cooling in outdoor off-grid scenarios.

Design, Simulation and Optimization of a Novel Transpired Tubular Solar Air Heater

In this paper, a novel tubular solar air heater is introduced. In this air heater, the hot boundary layer is drawn into the absorber tube and can provide thermal energy at moderate temperatures. Several different cases were simulated and a correlation was proposed to predict the collector’s effectiveness as a function Rayleigh number and Reynolds number. An equation was derived to find the effectiveness of this collector. Finally, a real case was studied with non-uniform solar flux distribution, as well as radiation heat loss. Good agreement was found between the results and those derived by the proposed analytical method. For different suction values, the first-law and the second-law efficiencies were calculated. Based on the exergy analysis, exergy destruction in absorption is the dominant factor that is unavoidable in low-temperature collectors. It was shown that there is an optimum suction value at which the second-law efficiency is maximized. At the optimum point, temperature rise can reach 54 K, which is hardly possible with a flat plate collector. Based on the exergy analysis, the relation between tube wall temperature and air outlet temperature in their dimensionless forms at the optimum working condition was derived, and it was shown that effectiveness at the optimum working condition is around 0.5. This means that the air temperature rise shall be half of the temperature difference between collector wall and the ambient temperatures. A high outlet temperature besides the low cost of construction and maintenance are the main advantages of this air heater. With such a high temperature rise, this type of collector can increase the use of solar energy in domestic applications.

A novel CFD model for design and performance prediction of recuperators for Indirect Evaporative Cooling

Indirect evaporative cooling (IEC) appears to be a highly promising technology for incorporating and/or substituting traditional air conditioning systems, as it can guarantee good cooling performance with a reduced environmental impact. In this study, a Computational Fluid Dynamics (CFD) model for design and performance prediction of recuperators for IEC systems with dry primary and secondary channels was developed. The model was validated against experimental data for a cross-flow recuperator, obtaining a maximum difference between numerical and experimental results of 4.9% for the secondary air outlet temperature, 5.3% for the primary air outlet temperature, and 8.1% for the dry-bulb effectiveness. After validation, the model was used to find a new plate geometry which guarantees a 12.5-15.9% improvement in the dry-bulb effectiveness, without an excessive increase in the pressure losses along the channels.

Experimental and numerical analysis of multi-layer micro channel applied to parabolic solar concentrator

There are numerous applications for micro-channel technology, but it has just a few applications in solar collectors. Therefore this research makes a clear contribution in this field by using a new design absorber in the concentrator, and the reflector was designed to focus the solar radiation on two sides. The solar concentrator system was attached to the tracking system to maintain the parabolic collector's perpendicularity to sun rays. This study investigates the experimental and numerical effects of the micro-channel technique on solar concentrator performance for different velocity values to meet the need for temperature differences, which gives Reynolds numbers varying from 1011 to 3273. The absorber plate was made from aluminum metal with 44 rectangular microchannels (0.3 m in length, 0.02 m in width, and 0.0009 m in height). The result indicated that the two-axis tracking system would increase output temperature by roughly 18 %. Outlet air temperature decreased significantly by 13.9 °C with changing flow rate from 0.009339 to 0.030235 kg/s. The highest efficiency was 91 % in March, 89 % in November, 80 % in February, 69.8 % in December and 65.5 % in January. A good agreement was obtained between numerical and experimental with a maximum deviation of 1.4, 1.7, 9.4 and 8.88 % for the glass cover, absorber plate, upper channel and lower channel, respectively.

Experimental assessment of the energy performance of a renewable air-cooling unit based on a dew-point indirect evaporative cooler and a desiccant wheel

Given the escalating energy consumption in cities worldwide, it is crucial to investigate the utilization of sustainable technologies and renewable energy sources. The number of empirical studies on the energy performance of hybrid air-cooling systems is limited. Therefore, the objective of this work is to experimentally study the energy performance of a novel renewable air-cooling unit. This prototype is mainly composed of a desiccant wheel and a dew-point indirect evaporative cooler to independently control the temperature, humidity, and carbon dioxide levels of indoor air. 64 experimental tests are carried out to fit an empirical model of this renewable air-cooling unit, focusing on outlet air conditions and the coefficient of performance. In addition, several performance indices are developed for desiccant wheel and dew-point indirect evaporative cooler: (i) moisture removal capacity; (ii) moisture removal capacity per unit of electrical power-consumption; (iii) dew-point efficiency and (iv) cooling capacity of dew-point indirect evaporative cooler per unit of electrical power-consumption. The highest values of dehumidification capacity, sensible cooling capacity and coefficient of performance for this renewable air-cooling unit are achieved for the most severe outdoor air conditions, namely 19.02 kg·h−1, 21.49 kW and 11.0, respectively. This work can serve as a reference for research on the feasibility of hybrid air-cooling systems in the scenarios of heat events and climate change world.

Research on Blast Furnace Air Outlet State Identification Model Based on Improved ResNet18

Research on Blast Furnace Air Outlet State Identification Model Based on Improved ResNet18

Impact of spray drying operating conditions on yield, secondary metabolites, antioxidant potential and storage quality of grape (Vitis vinifera L.) pomace powder

In the present investigation, spray drying independent operating conditions such as the inlet air temperature (A-IAT 130, 150 and 170 °C), outlet air temperature (B-OAT 60, 70 and 80 °C), needle speed (C-NS 3S, 4S, 5S), maltodextrin concentration (D-MD 10, 15, 20 %), pump speed (E-PS 5, 10, 15 mL/min) and water/grape pomace ratio (F-W/GP ratio 10, 15, 20) were optimized to develop the spray-dried grape pomace powder (SDGPP) with maximum yield. The impact of these conditions on total phenolic contents (TPC), total flavonoid contents (TFC), and antioxidant activity (DPPH· values) of SDGPP samples were analyzed. The independent spray drying factors (IAT, OAT, NS, MD, PS, and W/GP ratio) impart a strong direct effect (p ≤ 0.05) on powder yield, TPC, TFC, and DPPH· values. The interaction effects (A × B, A × C, A × D, A × E, A × F, B × C, B × D, B × E, B × F, C × D, C × E, C × F, D × E, D × F, and E × F) of independent variables were noted non-significant (p ≥ 0.05) for response values. After validation of the model and verification of results, the independents' variables were found in the range of 170 °C (IAT), 80 °C (OAT), 4S (NS), 15 % (MD), 10 mL/min (PS) and 15 (W/GP ratio) for yield (64.7 ± 1.18 %), TPC (7.66 ± 0.53 mg GAE/g), TFC (3.19 ± 0.30 mg CE/g) and DPPH· 140.3 ± 1.59 (100 µL/mL), respectively. The decrease in TPC, TFC, and DPPH· values of SDGPP samples was noted during 60 days of storage at 25 ± 2 °C and 65 ± 5 % RH (p ≤ 0.05) but not greater than unprocessed samples. It could be concluded that the protection of phenolic contents and retention of antioxidant activity of dried powders can be achieved at optimized spray drying conditions for discerning food and byproduct processing industries.

A decentralized control strategy for improved batch tablet coating process operation

This paper proposes a control strategy for batch tablet film-coating processes using readily available process instrumentation. Outlet air conditions (temperature and relative humidity), which impact coating quality, are controlled by the manipulation of inlet air temperature and coating spray rate. Controller design, tuning and validation rely on the use of a dynamic process simulator, calibrated using data collected from a pilot plant coating unit. The final 2 × 2 decentralized PI controller demonstrated good performance for both setpoint tracking and disturbance rejection in simulation. Additionally, controlled variable setpoints were determined to maximize plant profits considering batch duration and energy consumption as optimization criteria. For the case study considered, the total batch processing time can potentially be reduced by 40 % while simultaneously reducing energy usage by 30 %, in comparison with the more conservative fixed recipe approach typically adopted in production.

Impact of optimized gas-liquid separator on temperature and frost distribution in electric vehicle heat pump AC

In the context of low temperatures, the outdoor evaporator surface in an electric vehicle's heat pump air conditioning system tends to accumulate frost unevenly. This uneven frosting occurs due to the varying heat exchange capacity of the refrigerant's two phases within the evaporator. Any reduction in the heat exchanger's capacity would lead to a negative impact on system performance. To address these challenges, this study introduces a gas–liquid separator placed in front of the outdoor evaporator. The aim was to enhance both the outdoor evaporator's performance and the overall system efficiency while investigating frost formation and heat distribution in the outdoor evaporator within a heat pump air conditioning system. The research outcomes demonstrate that the gas–liquid separator can effectively enhance evaporating pressure by regulating the opening degree of the gas-phase bypass valve. Optimal performance is achieved with the gas-phase branch bypass valve set between 20% and 30%, ensuring a stable operational condition and higher evaporating pressure. Moreover, the incorporation of a gas–liquid separator could lead to significant improvements in system performance, with increases of 6.9% in heat capacity and 7.4% in COP observed. Additionally, this enhancement extends to the outlet air temperature, showing improvements ranging from 3.6% to 11.2%.

Experimental assessment of a solar vortex engine integrated with sensible TES at different collector configurations

This study presents an experimental investigation of the effect of different solar collector geometrical parameters on the solar vortex engine's (SVE) performance. The first parametric study is concerned with a solar vortex power generation system's diameter, inlet height, and thermal energy storage (TES) extension. The experimental results revealed that extending the TES by 1 m outside the canopy significantly increases thermal efficiency by 62 %. In addition, increasing the diameter of the solar collector from 8.8 m to 10.8 m, with an extra 1 m extended TES area, increased the air temperature rise by 57 %, while the outlet air velocity increased by 32 %. On the other hand, a reduction in the collector inlet height from 0.2 m to 0.15 increased the air temperature rise while decreasing the outlet air velocity and power output potential by mean values of 19 % and 48 %, respectively. The enhancement obtained from the extended area of TES is an important finding, as it increased the air temperature for a larger canopy size without extra cost. Therefore, increasing the absorption area or the TES outside the canopy is recommended. Also, further studies are essential to correlate the inlet height to the system's performance.

Retrofitting solar air heaters in New Zealand schools – A randomized crossover intervention study

Most New Zealand (NZ) schools rely on natural ventilation and are often inadequately ventilated in winter. NZ school hours typically span from 9 a.m. to 3 p.m. and are well aligned with optimum solar radiation. Existing classrooms could therefore be heated and ventilated using retrofitted solar energy applications. To investigate the suitability of a commercially available solar air heater (SAH) to improve ventilation, a randomized crossover intervention study was conducted in 12 classrooms from six primary schools in Palmerston North, NZ, during the winter of 2014. Typical performance results showed a mean (standard deviation, SD) SAH outlet air temperature of 29.2 (10.4) °C at a mean (SD) velocity of 0.7 (0.3) m·s-1. During most school periods (64–99%) classrooms maintained required thermal comfort. The concurrent use of the extant heaters was reduced, and carbon dioxide levels were improved, lowering exposure for occupants. This study confirmed that retrofitting SAHs contributed to improved classroom ventilation, increased thermal comfort and reduced energy use. Optimising performance would require design improvements to improve airflow in order to comply with NZ ventilation and indoor air quality requirements for schools.

A study on natural ventilation of dormitories for college students in northeast China during spring: A case of linear-shaped dormitory buildings

This study employed computational fluid dynamics to investigate the natural ventilation efficiency and indoor air temperature changes in different rooms of a linear-shaped dormitory building at a university in northeastern China during the spring season. Using a four-student dormitory in Jilin City as a physical model. Volume ratio of air age curves, depicting indoor air quality, are constructed based on air age values. Due to the dormitory building's symmetry, five wind angles, averaged from 0° to 90° (N - E), are chosen as typical. The results indicate that, following adequate ventilation, the average indoor air temperature (Temstabilize) can be stabilized above 11 °C in rooms located on the leeward side of the dormitory building. Specifically, rooms located on the upwind area at wind angles of 22.5° and 45°, as well as rooms near the environmental air inlets and outlets at wind angles of 67.5° and 90°, can maintain an average air temperature above 15 °C. However, the minimum continuous ventilation time (Tmin) required for these rooms exceeds 1200 s. On the windward side of the dormitory building, rooms near the environmental air inlets and outlets exhibit high ventilation efficiency, but the air temperature in these rooms decreases more rapidly. When the wind angle is 45°, 67.5°, or 90°, the average indoor temperature in these rooms falls below 11 °C. Through normalization analysis, a significant linear relationship is observed between Tmin and Temstabilize data, represented by the numerical relationship Tminnorm=1.0134×Temstabilizenorm. The findings of this study are valuable for assisting students in developing ventilation plans and can also serve as a reference for architects designing dormitory buildings based on prevailing wind directions in the area.

Experimental and numerical investigation of a real-scale air to multiple PCM heat exchanger

Energy consumption by residential sectors has proliferated due to urbanization and lifestyle changes. Passive cooling and heating systems can reduce energy consumption and CO2 emissions in residential and commercial sectors. Phase change materials provide an efficient solution for passive energy storage, addressing a building's needs for free cooling and heating. These materials absorb and release heat energy, enhancing the overall efficiency of the energy management system. By employing energy storage devices, it becomes feasible to reduce and shift peak loads to off-peak hours. This study optimized the size and configuration of air-to-multiple PCM heat exchanger through the utilization of a 2D ANSYS (Fluent 19.2) model. This study employs multiple phase change materials (PCMs) with varying melting temperatures as a heat transfer technique to reduce the melting and solidifying times of the PCMs. Furthermore, it was observed that the arrangement of PCMs in series affected melting and solidification times, so two scenarios have been examined. The air-to-multiple PCM system has been investigated through numerical simulations and experimental analyses, focusing on the liquid fractions within the PCM and the outlet air temperatures across the air channels. The total time for entirely melting PCMs RT25HC and RT21HC is less than 4 h, but the solidification time for PCM-RT21HC needs more than 12 h. In both scenarios, PCM-RT21HC melted first, while PCM-RT25HC solidified first.