Maximum Hourly Research Articles

Particulate Matter in the American Southwest: Detection and Analysis of Dust Storms Using Surface Measurements and Ground-Based LIDAR

This research study focuses on the coupling between particulate matter and the planetary boundary layer. Particulate matter affects human health and it is a complex mixture of suspended substances. Various sources of particulate matter include volcanic eruptions, soil lofted by strong winds, wildfires, and particles formed from chemical reactions of gas-phase emissions. Strong winds are one source of dust pollution when they loft soil particles. Particulate matter and the planetary boundary layer are closely linked. The planetary boundary layer plays a critical role in meteorology and particulate matter concentrations due to its involvement in energy, latent heat, and mass transfer with the free troposphere. Currently, there has been no research on the impact of dust events on the planetary boundary layer in our region, El Paso, Texas, which is located on one of the biggest sources of dust in the Western Hemisphere, the Chihuahuan Desert. In this study, we used PM10 concentrations to detect dust events during the 2016–2022 period in the El Paso region. During the study period, we observed 74 dust events. The dust events were categorized as synoptic or convective cases. Synoptic cases are associated with cold fronts, while convective cases are associated with local convective systems such as thunderstorms. We observed that synoptic cases occurred most frequently during springtime, while convective cases were more frequent during summer monsoon months. Synoptic cases tend to occur earlier in the afternoon with lower temperatures, while convective cases tend to occur in the late evening with higher temperatures. We also found that the planetary boundary layer height collapsed after the maximum hourly PM10 concentration and then the boundary layer returned to its original height.

Holistic non-linear optimization of the layout, sizing, and operation of a district heating plant

A large fraction of district heating networks in Europe are still operating without thermal energy storage. While offering operational flexibility, the presence of energy storage complicates the problems of optimal sizing and control of the heat production plant. This necessitates a novel approach to system sizing based on non-linear programming in order to capture the system’s thermal response and inertia. Therefore, the present study focuses on such a typical plant in France and describes a holistic approach to optimize the capacities/parameters of system components, positions of the energy sources, as well as hourly flow rates. Such a simultaneous tuning of the system parameters and operating variables is essential to maximize the cost savings over the system's lifetime. The proposed framework here maintains the original non-linear form of the objective function and the constraints for more accuracy while allowing precise modeling of the thermally stratified storage tank by decoupling its calculations at a lower simulation level. Hence, the computation time in MATLAB® R2020A is mostly below 20 min on a typical personal computer. The lowest levelized cost of heat (57.259 EUR/MWh) is achieved when placing the gas boiler on a parallel line between the biomass boiler and the storage tank while sizing the two boilers using fractions of 0.33 and 0.73 of the maximum hourly demand, respectively, as well as a storage volume of 318.9 m3. Such relatively small storage reduces the lifecycle costs by a maximum of 1.34 % while reducing the specific carbon emissions by 17.33 %. Besides, it dampens the fluctuations in supply flow rates, minimizes unnecessary flow recirculation, and ensures a stable heat supply. Overall, thermal storage has a reasonable positive impact from an economic perspective, but a substantial impact on operational flexibility and mitigated carbon emissions.

The current landscape of emergency medicine resident scheduling.

The Accreditation Council for Graduate Medical Education (ACGME) and Residency Review Committee oversee resident physician work hours with additional specifics for U.S. emergency medicine (EM) residency programs. While there are maximum work hours, the regulatory bodies do not describe minimum work hours to achieve competency, leading to variable scheduling practices. This study aimed to understand the current landscape of U.S. EM residency scheduling given the expansion of programs, evolution of policies, and increased emphasis on wellness. We conducted a cross-sectional study to assess current strategies of U.S. EM residency scheduling. The RedCap survey was sent to all ACGME-accredited EM residency programs across the United States via individualized emails between January 10, 2023, and March 15, 2023. Data were combined using Microsoft Excel. A total of 138 of 278 (50%) programs responded to the survey. A total of 73.2% of programs were using thirteen 28-day blocks with the remainder using twelve 1-month blocks or reported "other" block scheduling. The number of blocks in the ED increases with each postgraduate year (PGY). For PGY-1 through PGY-3, the most commonly used shift duration was 9 h. The mean total shifts per ED block and hours worked per ED block are as follows: 19 shifts and 185.1 h (PGY-1), 18.2 shifts and 173.9 h (PGY-2), 17.3 shifts and 163.6 h (PGY-3), and 14.8 shifts and 157.2 h (PGY-4). Programs provide a median for 4 weeks of vacation per year of residency. Given the expansion of U.S. EM residency programs, we reevaluated the landscape of resident scheduling. We described scheduling patterns related to night shifts, vacations, requested time off, conference coverage, charting time, and circadian rhythms. Programs should utilize these data as a starting point for setting a clinical experience for their residents.

Case study on the formation of a torrential‐rainfall‐producing southwest vortex: Backward trajectory analyses and sensitivity simulations

AbstractThe southwest vortices (SWVs) are a unique type of mesoscale vortex that frequently induce torrential rainfall in China. In this study, we focused a long‐lived quasi‐stationary SWV, which was the primary system for producing an extremely heavy rainstorm within/around Sichuan (the maximum hourly precipitation was ~103.8 mm) in Mid July 2021. After reproduced the SWV's formation by using Weather Research and Forecasting model, we conducted trajectory analyses and topography sensitivity simulations to understand the effects of complicated topography on the vortex's formation. It is found that, the regions south and southwest of the SWV acted as the most important source regions for the air clusters that formed the SWV (proportion ≥ 65%), and the air clusters originated from the upper layer contributed the most (≥60%). Of these, the air clusters sourced from the upper layer southwest and south of the SWV played the most important role in the SWV's formation, as their increase in cyclonic vorticity and their contributions to trajectory number and vorticity were all much larger than those of the others. Sensitivity simulations indicated that, detailed topography features around the Sichuan Basin were crucial in determining the structure, intensity and precipitation of the SWV, whereas, the topography features were not a decisive factor for the SWV's formation. In summary, our findings are useful to enrich the current understanding of the SWVs' formation, which would be helpful to improve the related forecasts.

Simulation and Analysis of the Mesoscale Vortex Affecting the “21·7” Extreme Rainstorm in Henan

From 17 to 22 July 2021, the “21·7” extreme rainfall event (“21·7” ERE) hit Henan Province, breaking the record for mainland China with a maximum hourly rainfall of 201.9 mm at the Zhengzhou station. The long-lived (20 h) mesoscale Huang-Huai vortex (HHV) was an important system that directly affected the major rainfall stage, including the extreme hourly rainfall. This study investigates the formation and development mechanism of the HHV, as well as its association with the simulation of extreme hourly rainfall through numerical simulations. The simulated rainfall and radar composite reflectivity were in good agreement with the observations, thus effectively reproducing the generation and developmental process of the HHV. The analysis results showed that the HHV initially formed at 850 hPa on 19 July at 1800 UTC and eventually developed to 550 hPa. The positive feedback formed by the horizontal convergence and vertical vorticity transport was the main mechanism leading to the generation and deepening of the HHV. The stretching effect (STR) term played an absolutely dominant role in the increase in the vorticity tendency, and it primarily originated from the coupling effect of boundary layer jets (BLJs) and synoptic-weather-system-related low-level jets (SLLJs). The accurate simulation of the HHV allowed the early rainfall to reasonably reproduce the surface cold pool near the Zhengzhou station, and then the cooperation of the SLLJs, the BLJs, and the cold pool made the simulated extreme hourly rainfall exactly close to the Zhengzhou station, but with a weaker intensity, due to the fact that the HHV moved northeastward after its formation, resulting in a narrow range of southerly flow in southern Henan, which is not conducive to convective triggering in the southerly flow.

Does Overtime Matter for Firm Performance: Evidence from Taiwan?

By employing the unique data related to employee overtime complaints about the firms listed in the financial industry of Taiwan Stock Exchange, we explore whether firm performance would be affected by several overtime complaints issues including complaints of maximum working hours exceeded, overtime without pay, and overtime without records. We then reveal the following essential findings. First, the firms with employee overtime complaints would not enhance firm performance. Second, complaints of maximum working hours exceeded would have significant negative impacts on firm performance as compared with firm performance affected by either complaints of overtime without records or complaints of overtime without pay, indicating that employee’s complaints about overtime should not be neglected by enterprises. Third, we still show that the firm with better financial performance such as higher net profit ratio and well-functioned board structure like small board size would have better firm performance.

Prediction of Autumn Ozone Concentration in the Pearl River Delta Based on Machine Learning

Based on the observation data of the daily maximum 8-hour ozone (O3) average concentration[MDA8-O3, ρ(O3-8h)] and meteorological reanalysis data in the Pearl River Delta Region from 2015 to 2022, four machine learning methods, i.e., support vector machine regression (SVR), random forest (RF), multi-layer perceptron (MLP), and lightweight gradient boosting machine (LG) were used to establish MDA8-O3 prediction models. The results showed that the SVR model had the best prediction performance on MDA8-O3 during the whole year, the coefficient of determination (R2) reached 0.86, and the root mean square error (RMSE) and mean absolute error (MAE) were 16.3 μg·m-3 and 12.3 μg·m-3, respectively. The prediction performance of the SVR model in autumn was still slightly better than that of LG and MLP, with R2,RMSE,and MAE values of 0.88, 19.8 μg·m-3,and 16.1 μg·m-3, respectively. The RF model performed the worst in the autumn prediction. In addition, the models trained by data from the whole year had better prediction ability on autumn MDA8-O3 than that of those only trained by autumn data, and the R2 differed 0.08-0.14.

Estimation of Return Level for Maximum Daily and Hourly Precipitation in Nagano Prefecture, Japan, Using the Extreme Value Theory

Estimation of Return Level for Maximum Daily and Hourly Precipitation in Nagano Prefecture, Japan, Using the Extreme Value Theory

Side effect of using N95 mask on oxygen saturation, respiration rate and pulse rate of health workers in Jakarta

The new normal era brings people new habits, one of which is wearing masks. The particulate respirator N95 mask (N95 mask) is the mask with the highest filtration, but there are some complaints regarding its use, one of which is difficulty breathing. Therefore, this study aims to determine whether there is an effect of using an N95 mask on oxygen saturation (SpO2), respiratory rate (RR) and pulse rate (PR). This study uses a convenience sampling technique with a sample size of 60 respondents. The research design used was a quasi-experimental design with a one-group pre and post-test design. Data analysis used the Wilcoxon test with p <0.0001, which means that there are differences in the results of SpO2, RR, and PR before and after using the N95 mask. Suggestions for health workers and policymakers in Indonesia to be able to apply the maximum hours of using N95 masks so that health workers avoid illness, disability, or discomfort which can maintain optimal performance.

Economics of renewable hydrogen production using wind and solar energy: A case study for Queensland, Australia

This study presents a technoeconomic analysis of renewables-based hydrogen production in Queensland, Australia under Optimistic, Reference and Pessimistic scenarios to address uncertainty in cost predictions. The goal of the work was to ascertain if the target fam-gate cost of AUD 3/kg (approx. USD 2/kg) could be reached. Economies of scale and the learning rate concept were factored into the economic model to account for the effect of scale-up and cost reductions as electrolyser manufacturing capacity grows. The model assumes that small-scale to large-scale wind turbine (WT)-based and photovoltaic (PV)-based power generation plants are directly coupled with an electrolyser array and utilises hourly generation data for the Gladstone hydrogen-hub region. Employing first a commonly used simplified approach, the electrolyser array was sized based on the maximum hourly power available for hydrogen production. The initial results indicated that scale-up is very beneficial: the levelised cost of green hydrogen (LCOH) could decrease by 49% from $6.1/kg to $3.1/kg when scaling PV-based plant from 10 MW to 1 GW, and for WT-based plant by 36% from $5.8/kg to $3.7/kg. Then, impacts on the LCOH of incorporating curtailment of ineffective peak power and electrolyser overload capacity were investigated and shown to be significant. Also significant was the beneficial effect of recognising that electrolyser efficiency depends on input power. The latter two factors have mostly been overlooked in the literature. Incorporating in the model the influence on the LCOH of real-world electrolyser operational characteristics overcomes a shortcoming of the simplified sizing method, namely that a large portion of electrolyser capacity is under-utilised, leading to unnecessarily high values of the LCOH. It was found that AUD 3/kg is achievable if the electrolyser array is properly sized, which should help to incentivise large-scale renewable hydrogen projects in Australia and elsewhere.

Change in Electric Power Consumption in Mongolia in 2020 and the Impact of the COVID-19 Pandemic

This paper deals with the change in electric power (EP) consumption in Mongolia in 2020 based on data on the maximum and minimum EP consumption a day, provided by NPTG. The changes in EP consumption in Mongolia in detail as weekly or seasonal changes as well as the impact of the COVID-19 pandemic have not been clear, even though annual EP consumption was provided from the reports of the World Bank, IEA, and other international institutes as statistical data. Differences in the maximum average hourly and the minimum EP consumption in a day was 277 MWh (30.2%) and in the maximum and minimum daily EP consumption in 2020, which appeared in winter and summer, respectively, was 933 MWh (71.3%). Also, a 104-MWh (14.8%) drop was confirmed on special days like Naadam. To discuss the impact of COVID-19, the values of 2017 were used as a criterion for a year absent of a pandemic, and the stringency index, an indicator used to quantify the severity and stringency of government policies and measures, was introduced, and compared with the monthly EP consumption in 2020. The COVID-19 pandemic decreased the EP consumption of 40 MWh (2 to 6%) except in December due to the free-electricity policy. The EP consumption showed the dependency of the stringency index, particularly a clear drop over 50 of the index values. These new findings of EP consumption properties are expected to apply EP demand forecasting and make design plans for future EP systems in Mongolia.

The features of legal regulation of working hours

The institute of working time is an integral part of the system of labor law of the Russian state. The presence of standards providing for maximum working hours, as well as guarantees for its establishment and use, represent a certain indicator showing the level of development of society. Today’s changes in the global economy are leading to an increasing spread of atypical forms of employment. As a result, labor law is undergoing significant changes, giving rise to new features of the legal regulation of labor relations. For example, the key feature of the working hours of remote workers is the possibility of its independent distribution by the employee. In the article, the authors analyze some problems arising in the field of legal regulation of the working hours of remote workers, law enforcement practice, and also offer ways to improve labor legislation in this area.

The most extreme rainfall erosivity event ever recorded in China up to 2022: the 7.20 storm in Henan Province

Abstract. Severe water erosion occurs during extreme storm events. Such an exceedingly severe storm occurred in Zhengzhou in central China on 20 July 2021 (the 7.20 storm). The magnitude and frequency of occurrence of this storm event were examined in terms of how erosive it was. To contextualize this extreme event, hourly rainfall data from 2420 automatic meteorological stations in China from 1951 to 2021 were analyzed to (1) characterize the spatial and temporal distribution of the rainfall amount and rainfall erosivity of the 7.20 storm, (2) evaluate the average recurrence interval of the maximum daily and event rainfall erosivity, and (3) establish the geographical distribution of the maximum daily and event rainfall erosivity in China. The center of the 7.20 storm moved from southeast to northwest in Henan Province, and the most intense period of rainfall occurred in the middle and late stages of the storm. Zhengzhou Meteorological Station happened to be aligned with the center of the storm, with a maximum daily rainfall of 552.5 mm and a maximum hourly rainfall intensity of 201.9 mm h−1. The average recurrence intervals of the maximum daily rainfall erosivity (43 354±1863 MJ mm ha−1 h−1) and the maximum event rainfall erosivity (58 874±2351 MJ mm ha−1 h−1) were estimated to be about 19 200 and 53 700 years, respectively, assuming the log-Pearson type-III distribution, and these were the maximum rainfall erosivities ever recorded among 2420 meteorological stations in mainland China up to 2022. The 7.20 storm suggests that the most erosive of storms does not necessarily occur in the wettest places in southern China, and these can occur in mid-latitude around 35∘ N with a moderate mean annual rainfall of 566.7 mm in Zhengzhou.

Experimental investigation of a desalination system using porous carbon tube as a humidification media with swirl flow

Humidification-dehumidification (HDH) technology is a technique for small-scale water desalination applications based on carrier gas humidification motivated by thermal energy. The present work introduces an experimental investigation of a desalination unit based on HDH method. The main objective of this study is to evaluate the heat and mass transport properties of porous carbon tubes (PCT) as a humidification medium with swirl flow for HDH unit. Processes for transferring heat and mass are investigated at varied the temperatures of water and air, water-to-air mass ratios (MR), and helical flow channel pitch (HCP). The performance analysis is investigated based on some of performance metrics such as gained output ratio (GOR), humidification efficiency (ηH), exergy efficiency (ηex), sustainability indicator (SI), and water cost (WC). Results indicate that the increase in MR and HCP increases all of performance parameters. High values of MR based on low air flow rate decrease the entropy generation and enhance the exergy efficiency. The humidity efficiency and GOR improve with the rise in the MR based on the water flow rate. The study of sustainability indicator shows that the proposed system has possibilities of doing business. It still has room for energy improvement and losses, though. The system's usability will increase after these modifications are made. When the process temperature associated with heating the feed water or/and input air rises, more freshwater is produced. The proposed system's maximum hourly yield reaches about 0.225 L with cost 0.078 cent. The best value of GOR, exergy efficiency, humidification efficiency and suitability indicator performed by the current system are about 3, 51.67 %, 48.72 % and 2.07 respectively.

Surrogate model of adaptive thermal comfort of a social housing in the Dominican Republic micro-climates: a predictive approach toward sustainable buildings

ABSTRACTAdaptive thermal comfort is essential for guaranteeing the well-being of building occupants. Therefore, this study emphasizes its importance and applies advanced computational techniques as a surrogate model and sensitivity analysis for an in-depth analysis of a social housing in the Dominican Republic evaluated under five micro-climates. The methodology includes a computational design with an energetic simulation. An adaptive model was developed following the ASHRAE-55 standard, and an artificial neural network was trained to predict comfort temperature. The results showed that Neiba city, corresponding to a hot semi-arid climate, presented the maximum hours of discomfort (8463), representing 96.6% of the total annual hours with a cooling degree day of 157.5, whereas Constanza city, corresponding to the oceanic climate, reported 2025 hours of discomfort (23.1%) and a cooling degree day of 48. The surrogate model based on artificial neural networks achieved a coefficient of determination of 0.9998, and the sensitivity analysis revealed a more significant influence of radiant temperature (55.96%) over comfort temperature. Finally, this study highlights the significance of adaptive thermal comfort in building design and the potential of surrogate models for energy analysis. Therefore, it is necessary to implement passive strategies to enhance indoor thermal comfort in a sustainable building sector.

Associations between weekly gestational exposure of fine particulate matter, ozone, and nitrogen dioxide and preterm birth in a North Carolina Birth Cohort, 2003-2015.

Preterm birth (PTB; <37 weeks completed gestation) is associated with exposure to air pollution, though variability in association magnitude and direction across exposure windows exists. We evaluated associations between weekly gestational exposure to fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3) with PTB in a North Carolina Birth Cohort from 2003 to 2015 (N = 1,367,517). Daily average PM2.5 and daily 8-hour maximum NO2 concentration estimates were obtained from a hybrid ensemble model with a spatial resolution of 1 km2. Daily 8-hour maximum census tract-level concentration estimates for O3 were obtained from the EPA's Fused Air Quality Surface Using Downscaling model. Air pollutant concentrations were linked by census tract to residential address at delivery and averaged across each week of pregnancy. Modified Poisson regression models with robust errors were used to estimate risk differences (RD [95% confidence intervals (CI)]) for an interquartile range increase in pollutants per 10,000 births, adjusted for potential confounders. Associations were similar in magnitude across weeks. We observed positive associations for PM2.5 and O3 exposures, but generally null associations with NO2. RDs ranged from 15 (95% CI = 11, 18) to 32 (27, 37) per 10,000 births for PM2.5; from -7 (-14, -1) to 0 (-5, 4) for NO2; and from 4 (1, 7) to 13 (10, 16) for O3. Our results show that increased PM2.5 exposure is associated with an increased risk of PTB across gestational weeks, and these associations persist in multipollutant models with NO2 and/or O3.

A bi-objective model for aircraft and crew recovery considering individual flight legs and maintenance requirements

This paper proposes a new bi-objective aircraft and crew recovery model. Unlike previous researches, the proposed model considers all individual flight legs in the recovery process. The objective functions minimize the recovery cost regarding crew swapping, flight cancellation, flight delay, and crew deadhead costs. Besides, the crew sit time is reduced considering the maximum legal working hours and the minimum essential rest time. Moreover, maintenance operations can be done during the ground time, not necessarily at the end of duty day. The model is never infeasible because flight cancelation is an alternative solution for recovering a schedule. A modified Tabu Search (TS) approach has been developed to solve the model. The performance of the model and solution approach is examined by several test problems in small, medium, and large scales. The results indicate that TS reaches optimal and close-optimal in a short computational time, especially in large scale problems.

Chemical composition and morphology of PM2.5 in a rural valley during Chinese New Year's Eve: Impact of firework/firecracker display

To study the effect of fireworks/firecrackers (FF) display on aerosol particles, the chemical composition and morphology of fine aerosol particles (PM2.5) collected in a rural valley of north China in the Chinese New Year's Eve (CNYE) were analyzed. The results showed that PM2.5 was much lower in the 2022 CNYE with little influence by FF due to the strict no-FF display policy for the 2022 Winter Olympic Games. In contrast, PM2.5 was significantly affected by FF display in the 2023 CNYE with the maximum hourly PM2.5 mass concentrations reaching 1200 μg m−3. The value was even much higher than that in near-by cities. Chemical analysis showed that organic matter (24.5 wt% of total PM2.5) was the most abundant in the CNYE, followed by K+ (15.3 wt%), SO42− (12.3 wt%), and Cl− (9.9 wt%). The mass concentrations of K+, Mg2+, Cu, Sr, and Ba were as 22.0 to 41.4 times as those before the CNYE. The concentrations of elemental carbon, Cl−, SO42−, and Ti were as 3.7 to 12.3 times as those before the CNYE. Further analysis by scanning electron microscope coupled with energy dispersive X-ray spectrometer revealed that carbonaceous particles in the CNYE contained more S, Cl, K and heavy metals compared with that before the CNYE. Most of the non-carbonaceous particles in the CNYE were K-rich, Mg-rich, Al-rich, and Ba-rich, with spherical and near-spherical shapes, which were much different from those before the CNYE with irregular shapes. The different morphologies of non-carbonaceous particles can have much different optical properties, which should be further evaluated. The results above suggested that the PM2.5 mass concentration in rural valleys in the CNYE was extremely high in a short time and more attention should be paid in future policy making to improve air quality.

Experimental investigation of a novel design of cavity receiver for a parabolic dish collector humidification-dehumidification desalination system

In this study, a desalination cycle using a humidification-dehumidification method equipped with a parabolic dish collector has been experimentally designed and tested under the climatic conditions of Semnan City. A novel geometry of cylindrical-conical for parabolic dish collector’s cavity receiver was selected and used in this desalination system. For the experimental tests, four water samples were selected from the non-conventional brackish water sources in Semnan province. The performance of the desalination cycle was investigated for four days in the maximum period from 9:00 a.m. to 3:00 p.m. According to the results obtained from the tests, the maximum thermal efficiency of the collector with the cylindrical-conical cavity receiver for the test with water sample with electrical conductivity of 21,500 µS/cm was obtained as 45.49%. The highest water production rate was 0.966 l/day for a water sample with an electrical conductivity of 13,810 µS/cm. The average hourly water production rate for the saltiest water has reached the highest value, equivalent to 147.67 cm3/h. It was also found that there is an increasing trend of water production with an increase in the salinity of brackish water. The maximum hourly exergy efficiency of the system was 14.04% for a water sample with an electrical conductivity of 21,500 µS/cm. An increase in hourly exergy efficiency was observed with the increase in water salinity.

High power and energy density of a wavy PCM unit embedded in a solar air heater utilizing fractional porous media

This experimental and numerical investigation presents the optimization of a wavy PCM unit to obtain high power and energy density with and without porous media for solar air heater applications at low ambient temperature (12oC≤Ta≤24oC). Hence, paraffin wax as a thermal energy storage material and wire mesh as a porous media are selected in this investigation. The effect of the fractional porous region (25%≤ψ≤100%) and porosity (94%≤ϕ≤100%) of the PCM unit is investigated to obtain desired power and energy density. The obtained numerical results revealed that the porous fraction region (ψ) of 50% and porosity (ϕ) of 96% are the optimum value in wavy PCM unit to obtain high power and energy density. As an extension of this work, the optimized thermal energy storage unit is further utilized in an impinging jet solar air heater design to obtain instant and long thermal backups and, consequently, outlet air at high temperature. The wavy PCM unit embedded impinging jet solar air heater is experimentally investigated under outdoor conditions for two cases; viz, to obtain instant and long thermal backups. To obtain instant and long thermal backups, a full day and alternative operations are conducted. Whereas, in case of alternative operation, charging of the PCM unit is only done up to the maximum sunshine hour of the day and solar air heater is operated during the night to utilize stored thermal energy at high power and energy density to deliver outlet air at high temperature for the long duration. Moreover, the experimental results revealed a maximum outlet air temperature of 59°C at 0.01 kg/s and a significant thermal energy backup up to 5 h at an outlet air temperature gain of ≥ 5°C. The economic analysis is also conducted for the solar air heater design and the operating cost is obtained as 0.02 INR/kWh at the optimum condition.