Air Mass Flow Rate Research Articles

Effect of Channel Size on Air-Cooling Performance in Interior Permanent Magnet Motor Driving Aviation Fans at High Altitude

Abstract To enhance worldwide environmental conditions, the air transport industry must drastically reduce carbon dioxide emissions. Electrification of aircraft propulsion systems is one way to meet this demand. In particular, the focus is on obtaining single-aisle aircraft with partial turbo-electric propulsion and approximately 150 passenger seats by the 2030s. To develop a single-aisle aircraft with partial turbo-electric propulsion, an air-cooled interior permanent magnet (IPM) motor with an output of 2 MW is desired. One of the most difficult problems in air cooling is that air-cooling performance decreases with increasing altitude because the air density decreases. To investigate the effect of altitude on air-cooling performance in the IPM motor, the authors formulated mathematical system equations to describe heat transfer inside the target air-cooled IPM motor, and mathematical analytical solutions were obtained. The most severe condition is the top-of-climb condition. For this condition, a designer should choose cooling air mass flow rates that keep the temperature of the permanent magnets below the maximum temperature limit of 100 °C and the temperature of the coils below the maximum temperature limit of 250 °C. Here, the sizes of the air-cooling channels strongly affect air cooling with the IPM motor. In this paper, the authors briefly review the mathematical formulations and their solutions, investigate the effect of channel size on air-cooling performance in an IPM motor, and explore the optimum configuration and settings for the air cooling channels.

KARAKTERISTIK PENGERING SURYA (SOLAR DRYER) DENGAN TURBIN VENTILATOR

Pada penelitian terdahulu, alat pengering yang dianalisis adalah pengering surya dengan kolektor sekunder, rak bertingkat dan exhaust fan. Penelitian tersebut berhasil mengatasi fenomena lambatnya proses pengeringan akibat terperangkapnya uap air yang keluar dari sampel (tumpukan gabah) pada rak pengering bawah pada rak pengering tengah dan atas. Selain itu temperatur udara dalam kabin pengering sudah tidak melebihi 70oC sehingga kualitas produk (gabah) yang dikeringkan terjamin. Kekurangan pada alat pengering tersebut adalah exhaust fan yang digunakan membutuhkan supply energi listrik sehingga efisiensi pengering masih rendah. Untuk mengatasi kekurangan tersebut, maka pada penelitian ini akan dilakukan modifikasi dengan mengganti exhaust fan dengan turbin ventilator Penelitian ini dilaksanakan di Laboratorium Teknik Mesin, Fakultas Teknik, Universitas Cenderawasih karena telah memiliki peralatan penunjang yang sudah memadai. Metode yang digunakan adalah metode eksperimen yakni membuat sebuah pengering surya tipe rak bertingkat (3 tingkat) dengankolektor sekunder dan turbin ventilator. Kemudian dilakukan pengujian untuk mengetahui karakteristiknya. Hasil penelitian menunjukkan bahwa penambahan turbin ventilator merupakan solusi untuk mengatasi penggunaan energi listrik pada solar dryer. Proses pengeringan pada rak pengering 2 (tengah) dan 3 (atas) tetap berlangsung dengan cepat karena turbin ventilator bisa bekerja seperti exhaust fan. Laju aliran massa udara keluar dari pengering juga baik sehingga temperatur dalam kabinpengering tetap terjaga (tidak melebihi 70oC). Waktu pengeringan gabah dari kadar air awal 24,8% menjadi kadar air akhir 14% adalah 5 jam (rak 1); 6 jam (rak 2) dan 6 jam (rak 3). Efisiensi pengeringan maksimum yang diperoleh adalah 27,35% (rak 1); 24,05% (rak 2); 22,95% (rak 3); 24,78% (rata-rata).

Design and partial-load operation of a reversible Solid Oxide Cell system with molten salts thermal storage

The increasing penetration of renewable energy sources in the electricity mix requires efficient storage solutions on the seasonal scale. Reversible Solid Oxide Cell (rSOC) systems are receiving increased attention as viable options to fulfil this requirement. In this work, a MW-scale rSOC system capable of working over a large operating window is studied via modelling on Aspen Plus®. To ease the thermal integration, a molten salt thermal storage is coupled to the system, enabling heat recovery in fuel cell mode, which is then exploited for water evaporation in electrolysis mode. The rSOC stack is designed to operate exothermically in the electrolysis mode at nominal load. In both modalities, the air mass flow rate is regulated to control the stack temperature, while limiting the in-out gradients within 100°C. At nominal load, the system achieves an electrical efficiency of 52% in fuel cell mode and of 87% in electrolysis mode. The operation at low partial loads, due to the decrease of the air flow rate, requires an additional high-temperature heat source to guarantee the heat integration. In this regard, the adoption of an electrical resistance in electrolysis mode and a hydrogen-fed combustor in fuel cell mode are selected as viable solutions to amplify the operating range of the system. As a results, the system can be operated down to the 30% of the stack nominal power in both modalities, where the system achieves an electric efficiency of 44% and 80% in fuel cell and electrolysis mode, respectively.

A low‐energy approach to processing large‐scale airflow

AbstractA simplified solar updraft device adapted from the Trombe wall concept was built to process large‐scale airflow using only solar energy. The performances were systematically studied using experimental measurements and numerical models, with the focus of investigating whether this device can generate enough airflow under low solar intensities, and developing a fast‐analytical mathematical model to effectively and efficiently find design rules for further application. The experimental results prove that the air mass flow rate generated by solar updraft in a 0.9 m2 solar updraft device can be as high as 75.6 kg/h when the solar radiation is only 120 W/m2. A comparison of two numerical models shows that it is feasible to develop a fast‐analytical tool based on widely available MATLAB with low demand for computing resources and to provide guidance on how a future device should be designed for particular applications. The study also investigated the effects of a wider range of solar radiation intensities, air channel height and thickness on the updraft performances (e.g., air temperature, airflow velocity, and mass flow rate).

ACAES systems to enhance the self-consumption rate of renewable electricity in sustainable energy communities

This paper aims to evaluate the optimal configuration of an Adiabatic Compressed Air Energy Storage (ACAES) system designed to achieve the best matching between power production from non-programmable Renewable Energy Sources (RES) power plants and power demand from final users. The electrical energy demand of a small town, with a maximum power load of about 10 MW, has been considered as case study. The electrical energy can be supplied by both a photovoltaic (PV) power plant and the grid. For the ACAES system, different sizes for compressor, turbine, thermal energy storage (TES) system and air storage reservoir have been evaluated by varying the air mass flow rate of turbomachines and the charging and discharging duration times, to enhance the share of the PV energy supplied to the end user. The best performance is achieved with a PV power plant rated at about 35 MW and an ACAES section characterized by a compressor/turbine rated power of about 25-35% of the maximum power load of the end user, with a charging time of about 10 hours and a discharging time of about 20 hours. The average round-trip efficiency of the ACAES system is around 70%. On the overall, the integrated PV-ACAES system allows to cover 66% of the yearly electrical energy demand.

Thermo-hydraulic performance of solar air heater with finned absorber plate forming multiple rectangular air flow passages in parallel under laminar flow conditions

The paper presents results of an analysis carried out using the governing equations to compare the heat transfer performance of a uniformly heated flat plate with longitudinal fins, which form multiple rectangular air flow passages in parallel below the plate and cover whole of the passage surface, with that of the low aspect ratio rectangular duct typical of conventional flat plate solar air heater at equal pumping power under laminar flow conditions. The heat transfer rate at equal pumping power for the plate with 1 mm thick steel fins at pitch of 25 mm and 40 mm is found to be about 2.7 and 2.5 times, respectively, over the duct without fins. The heat transfer study is followed by thermo-hydraulic performance study of the solar air heater with absorber plate having longitudinal fins forming multiple rectangular air flow passages in parallel. The finned solar air heater with low air mass flow rates has been found to provide 28–31 % better thermal efficiency than the conventional solar air heater at equal pumping power. The results of the study can be utilized for the development of enhanced performance finned solar air heater operating with low air mass rates to deliver high temperature air.

Rotating Detonations in Hollow and Flow-Through Combustors

This paper focuses on rotating detonation combustor (RDC) experiments involving two configurations, a hollow and flow-through RDC, using hydrogen–air and ethylene–air mixtures. Two air injection areas with gaps of 1.778 and 3.81 mm were used at different air mass flow rates of 0.2, 0.3, 0.4, and 0.5 kg/s and equivalence ratios from 0.6 to 2 in 0.2 increments. Results show repeatable detonations for hydrogen–air mixtures in both configurations; however, the detonative range is wider, stronger, and faster in the hollow configuration. Speeds exceeding the Chapman–Jouguet velocity and pressures matching the ideal model were observed. Sustained detonations for ethylene–air mixtures were not attained with the flow-through configuration. Installing a back plate to convert the configuration into a hollow combustor promoted rotating detonations with the ethylene–air mixture at select operating points. The results of this study showcase the strong promise of producing and sustaining rotating detonation in nonannular RDC configurations.

Optimizing model parameters of artificial neural networks to predict vehicle emissions

This paper presents a novel approach to predict carbon dioxide (CO2), nitrogen oxides (NOx), and carbon monoxide (CO) emissions of diesel vehicles using artificial neural network (ANN), which offer high degrees of accuracy and practicality. Six operating parameters (velocity, engine speed, engine torque, engine coolant temperature, fuel/air ratio, and intake air mass flow) collected through on-board diagnostic interface were used as predictors of exhaust emissions. The importance of each parameter to the emission predictions were comprehensively analyzed by comparing the coefficient of determination, root mean square error, cumulative emissions, and instantaneous emission rates. The emission prediction accuracy of ANN tends to increase as more parameters were considered as model inputs at the same time. However, the level of accuracy improvement depends on the input parameters. For CO2 emissions, engine torque and fuel/air ratio were good predictors for achieving high prediction accuracy. The relative importance of intake air mass flow rate and fuel/air ratio was high for NOx and CO predictions, respectively. In addition, the emission prediction accuracy of ANN depends on the vehicle type (Euro 5, Euro 6b, Euro 6d-temp). The emission prediction accuracy of vehicles equipped with after-treatment devices (selective catalytic reduction and lean NOx trap) was lower than that of vehicles without after-treatment devices.

Comparative study on the thermal characteristics of natural draft wet cooling tower with internal and external auxiliary fans

Auxiliary ventilation is an innovative approach for strengthening the thermal performance of natural draft wet cooling towers, which can be implemented with internal and external fans. In this study, a three-dimensional numerical model for cooling tower with these fans is established, with consideration of the existence or absence of air deflectors. To comparatively study the thermal performance of the above cooling towers, some critical parameters such as the air mass flow rate and circulating water temperature drop are computed, and the airflow and water temperature field are also investigated. Results manifest that external fans can enhance the air mass flow rate greater than internal fans under various crosswind velocities, while they are more effective in increasing the water temperature drop under a lower and a higher crosswind velocity, with a maximum increment of 8.5% and 10.0%, respectively. The addition of air deflectors narrows the high-velocity area, thus improving the uniformity of air distribution. The positive effect of air deflectors enhances with the increase of crosswind velocity, which decreases the water temperature drop of cooling tower with internal fans and that with external fans by 10.3% and 5.6% at most, respectively. This study can promote the engineering applications of auxiliary fans.

Prediction of outlet air characteristics and thermal performance of a symmetrical solar air heater via machine learning to develop a model-based operational control scheme-an experimental study.

This study develops reliable and robust machine learning (ML) models to predict the outlet air temperature and humidity and thermal efficiency of a solar air heater (SAH). Also, the application of predictive models for optimal control of the SAH operation is proposed. For this, the work contains three main parts: (a) a vertically-mounted symmetrical SAH was installed outside of a building room and operated throughout the winter of 2022. (b) By conducting experiments for five air mass flow rates, a large dataset with more than 62,500 sample points was collected. (c) Six input features containing time, environmental-related attributes, and SAH variables were applied to develop several state-of-the-art ML algorithms. To figure out the most accurate models for predicting output variables, the dataset was partitioned into three parts. Also, various modeling performance evaluation criteria were calculated and compared on the validation and test sets. Among these models, the gradient boosting machine algorithm based on LightGBM implementation achieved the best degree of generalization in modeling the target variables. The results demonstrated that the developed models obtained the lowest R-squared and the highest mean absolute percentage error of 0.9827 and 2.95%, respectively, on the test set. Moreover, the offline analysis of SAH operation based on the proposed control scheme demonstrated that 350 kWh of thermal energy can be generated during the application in the one-year winter season, 24% more than SAH operation without a model-based control strategy.

Closed collector –storage solar air heating system thermal performance: an experimental study

ABSTRACT A novel solar air heater design is proposed in the present study. The new design is a closed collector – storage solar air heater system (CCSSAHS) integrated with an internal finned heat exchanger filled with PCM. Two identical solar air heaters were manufactured for the sake of comparison. The first one was filled with RT42, and the second one was filled with RT50. The thermal performance of the solar air heaters was studied for RT42 and RT50, utilizing reflecting mirror; air mass flow rate, that is, 0.25, 0.045, and 0.065 kg/s; series and separation arrangements. For RT42, the experiments showed at 0.025 kg, with mirror, and series arrangement that the stored power, charging efficiency, discharged power, and discharging efficiency were 1255 W, 90.7%, 420 W, and 93.9%, respectively, while for RT50 were 1203 W, 87%, 332 W, and 88.1%, respectively. The highest air temperature difference between the exit and entrance of the solar air heater was found for RT42 at 0.025 kg/s with mirror for the separation arrangement, that is, 16.8°C. In addition, an economic evaluation was presented. CCSSAHS can satisfy tremendous industrial and domestic needs. The internal finned heat exchanger, the core component of the solar air heater, can be recycled from damaged air condition devices. The present proposed design combines the principle of recycling and clean energy to preserve the environment.

Experimental investigation on the performance of an advanced bi-fluid photovoltaic thermal solar collector system

This paper aims to investigate the effect of various mass flow rates of working fluids on the performances of the bi-fluid photovoltaic thermal (PVT) system and the integrated air-based type. The experiments were conducted for two outdoor cases, Case I and Case II. In each case, the mass flow rate of air was fixed at a value in both systems, while the mass flow rate of water was varied between two values in the bi-fluid PVT system. The observed results showed the performance of both systems can be improved by the optimum mass flow rates. The bi-fluid PVT system working with 0.1190 kgs−1 and 0.0102 kgs−1 of air and water flows has given 64.57 %, 12.64 %, and 99.33 % of thermal, electrical, and overall efficiencies, respectively. Furthermore, when the air-based was operating at the mass flow rate of 0.0446 kgs−1, the corresponding findings were 35.56 %, 12.56 %, and 70.54 % of thermal, electrical, and overall efficiencies. However, the electrical performance was also investigated for the connected PV modules. The maximum power output was 248 W and 223.7 W for Case I and Case II, respectively, as the highest values for different operating conditions. The positive results suggest the technology to be used for various usages.

Performance of an air-cooled photovoltaic/thermal system using micro heat pipe array

The performance of an air-cooled photovoltaic/thermal (PV/T) system based on micro heat pipe arrays (MHPAs) proposed in this paper was experimentally studied and analyzed. The results show that the MHPA-PV/T system has an excellent cooling effect under transient state. The temperature of PV cells can be decreased by 22.8 °C, and the power generation efficiency is increased by 30.9 %, while the corresponding temperature difference along the MHPA direction was only 0.77 °C. The temperature in the air duct increased by 34.1 % and presented a sharply upward trend in the early stage of operation, which was positively correlated with the solar irradiation. The overall efficiency was improved when the air mass flow rate increased from 0.0343818 kg/s to 0.0987572 kg/s, however, the increase in power generation efficiency was negligible compared to the increase in heat collecting efficiency. When the air mass flow rate was 0.0987572 kg/s, the power generation efficiency, heat collecting efficiency and overall efficiency were 38.12 %, 13.0 % and 65.90 %, respectively. According to the temperature under different air mass flow rate, it can be concluded that the temperature difference between inlet and outlet decreases with the increase of air mass flow rate. In addition, the system performance in different seasons was also analyzed. The research results will provide theoretical basis and data support for the practical application of the MHPA-PV/T system, and it is of great significance to achieve the strategic goal of “carbon peak and carbon neutrality” of China.

Thermal analysis and optimization of indirect flat evaporative coolers

• Analyzing the energy and exergy performance of indirect flat evaporative coolers on the basis of a verified numerical model and experimental correlation • Investigating the mechanism and theory of operation of indirect flat-panel evaporative coolers based on X-analysis • Calculating the entropy production rate of the flat-plate heat exchanger of the cooler Less attention and analysis have been given to cooling indirect evaporative coolers with different configurations and working air sources so far. This paper investigates the mechanism and theory of operation of indirect flat-panel evaporative coolers based on X-analysis. Then, based on the second law of thermodynamics analysis, the entropy production rate of the flat-plate heat exchanger of the cooler is calculated. As a result of this analysis, the optimal energy efficiency-evaporation efficiency and cooling capacity values are presented in terms of effective parameters in the design. It was concluded that dew point effectiveness and COP of the proposed system change monotonously with inlet mass flow rate, temperature and humidity ratio of primary air, respectively. The dew point effectiveness also varies monotonously with the mass flow rate ratio of secondary air to primary air. However, there exists an optimal mass flow rate ratio resulting in a maximum COP.

Computational Fluid Dynamics Simulation of a Fluid Catalytic Cracking Regenerator

The aim of this study is to simulate a Fluid Catalytic Cracking (FCC) Regenerator, of a local refinery, using the Fluent Ansys.13 program and subsequently to investigate the impact of the change in geometry on the unit’s performance. Three different geometrical models of FCC Regenerator were simulated. The Solid Works program was used to build up the computational domain and the commercial CFD code Ansys-Fluent 13 was used for meshing, models setup and solving. Three cases were examined: base case with a single air inlet, case one with five air inlets, and case two with five air inlets, however with the catalyst inlet axis raised by 100%. The results showed that the carbon solid mass content (used to represent the coke) decreases from 0.39 to 0.23 in the base case and to 0.12 in case one and to 0.19 in case two for the regenerated catalyst. Case one resulted in a decrease in carbon content by 100%, with a carbon monoxide emission of 10ppm (the base case at a value of 200ppm) which increased in case two to 100ppm. Furthermore the impact of air mass flow rate in case one (best case) was investigated starting with a mass flow rate of 29.5kg/s. The flow rate was further increased by 100% and 200% which resulted in a carbon mass content of 0.092 and 0.08 respectively.

Mathematical Model for Predicting the Development of Two-Phase Flow in a Horizontal Pipe

Prediction of the flow pattern is a central problms in multi-phase flow analysis. It is a vital point for researchers to accurately predict which flow pattern category types will occur at different flow rates. For this purpose, a mathematical model using the MATLAB (R2017b) computer program is developed for the prediction of gas-liquid two-phase flow patterns in a horizontal pipe with an inner diameter of 30mm under standard conditions. The properties of the air-water two-phase, the pipe geometry, and the flow rates of phases are defined to initiate the operating conditions. The mass flow rates of air and water changed from 0.002 to 0.004 kg/s and 0.672 to 1.334 kg/s, respectively. The impact of properties of the fluid and pipe diameters on two-phase flow configuration is considered to predict the impact of fluid properties on the flow pattern. The findings indicate that as the mass flux increases, the pipe diameters decrease, affecting the configuration of the flow pattern types. The mathematical model�s predicted results are validated by comparing with previous studies. In addition, good agreement is obtained when the predicted results are compared to the ongoing experiment of this research.

The experimental study of energy features for solar air heaters with different turbulator configurations

AbstractTo assess the thermal performance in the climate conditions of western and central Iraq, the advantages of using a solar air collector with various turbulator absorber plates are experimentally explored. Four distinct kinds of absorber plates are provided flat plate (F), triangular (T), rectangular (R), and circular (C) turbulators at different air mass flow rates. The collector's economic properties and overall thermal performance are compared to the conventional flat plate turbulator heating systems. The main findings suggest that delta turbulators improve collector economics and overall thermal performance by generating vortex and dampening the formation of the thermal boundary layer in the direction of airflow. Furthermore, when the mass flow rate increases, the thermal performance improves, and the efficiency increases for all mass flow rates, resulting in good thermal performance for the rectangular plate collector when compared to other collectors. When compared to other types of configurations, the daily average efficiency of solar air collectors for flat plate (F), triangular (T), rectangular (R), and circular (C) turbulators are 28%, 67%, 39%, and 48%, respectively, at 50° tilt angle while at 90° tilt angle they are 44%, 76%, 54%, and 63%, respectively, as ṁ = 0.0377 kg/s. The maximum daily average efficiency fitted with rectangular turbulators have about 86% at the largest ṁ = 0.1 kg/s. This study will also give a unique direction to the work trend in the western and central parts of Iraq throughout the winter months.

Design a low-cost, medium-scale, flat plate solar air heater: An experimental and simulation study

The most efficient solar air heater is expensive, and attempts to reduce costs lead to reduced efficiency. The current study presents a low-cost, medium-scale, flat plate solar air heater's design, simulation, and experimental thermal analysis. Carbon steel, thermocol, window glass, and aerosol spray paint were utilized for fabrication to decrease manufacturing costs. Initially, a mathematical model was developed, and experimental tests on this system were carried out with different absorber plates and glass covers in various weather conditions. The air mass flow rate of the collector is set at 0.073 kg/s. According to the experimental results, the solar air collector with a finned steel absorption plate, black paint, and double-glazing exhibit optimal performance. Under average solar radiation and ambient temperature of 910 W/m2 and 29.44 °C, respectively, the maximum thermal efficiency is 60.81 %, the average thermal efficiency is 56.01 %, and the average air temperature difference between the inlet and outlet is 40 °C. Whereas, for the solar air collector with plain steel absorber plate and single glazing, the least desirable performance was observed with a maximum collector efficiency of 45.76 %, an average thermal efficiency of 39.22 %, and an average air temperature difference of 20.14 °C between inlet and outlet under average solar radiation and ambient temperature of 810 W/m2 and 29.98 °C, respectively. Compared to the results, the thermal performance of solar air collectors with a finned steel absorption plate, black paint, and double-glazing was improved by 14 % to 20 % under different conditions. In addition, the solar air heater was designed, and a simulation study was performed in COMSOL Multiphysics software to find the temperature distribution of the glass cover and absorber plate. The experimental findings demonstrated that this convenient and cost-effective solar air collector was designed successfully and can be utilized in heating applications.

Investigating the Effect of Spherical Aluminum Particles on the Photothermal Performance of a Solar Air Collector

Recently, radiation-absorbing phase change material (PCM) for thermal storage that can discharge thermal energy on demand when no radiation is present has been developed and tested indoors. Organic materials with limited thermal conductivity slow down the thermal response processes when charging and discharging. For various industrial applications, much research is devoted to the introduction of solar collectors with the best possible integration of solar thermal collector and PCM in terms of both shape and material. In this study, the performance of a solar collector is examined in relation to the additive effects of aluminum particles in spherical capsules. For the transfer fluid temperature with the behavior of the heat storage, a mathematical model of the solar collector was created. The integrated system consists of two primary steps: a first phase that involves an isolated duct covered in glass, and a second step that involves an array of spherical capsules used as storage. The solar air collector is 1.32 m in width and 2.450 m in length. The PCM unit has a 7.7 cm diameter, 0.15 cm thickness, and is filled with a paraffin wax with concentrations between 0.1 and 0.5 weight of nanoparticle aluminum powder. The air mass flow rate varies from 0.03 kg/s up to 0.09 kg/s, while the temperature varied from 30 to 35 °C. The results obtained from experiments agreed with the predicted results. The reduction in charging time was approximately 70% as the cooling rate increased. The improvement of efficiency of thermal storage reached 76.8% and 71%, at mass flow rates 0.07 kg/s and 0.05 kg/s for pure paraffin wax. The overall thermal storage performance for the system was enhanced from 21.7% to 78.9%.

Energy and thermal performance of optimised hollow fibre liquid desiccant cooling and dehumidification systems in mediterranean regions: Modelling, validation and case study

The heat and mass transfer of liquid desiccant for dehumidification and cooling has been investigated in recent years as a promising energy-efficient technology to improve indoor thermal comfort. Limited studies, however, investigated integration strategies and energy performance of such systems in real buildings with performance correlations in building energy simulation software. This research considers a low-rise Greek apartment building constructed in 1981 as a case study. The optimal system sizing is determined via parametric analysis in the numerical modelling stage as: 1) air mass flow rate of 57 m3/h; 2) solution mass flow of 2.0 l/min; 3) solution inlet temperature of 14 °C; 4) solution concentration of 40%. Besides, the thermal and electrical COP correlations are derived from the inlet air temperature and relative humidity, with maximum value of 0.51 and 7.32 (inlet air temperature: 35 °C and relative humidity: 90%). The results show that by integrating two photovoltaic thermal (PVT) panels and a 300L water-based thermal storage tank into the desiccant cooler, such a hybrid system could achieve maximum COP value of 4.21 in the case study. Besides, the summer supply air thermal unacceptable level is reduced by at least 65% from 2535 h to 884 h.