Noor Moneer Basher¹, Omar Rafae Alomar^1,*, Omar Mohammed Ali², Diyar Abdullah Ahmed³

Frontiers in Heat and Mass Transfer, Vol.23, No.6, pp. 2001-2024, 2025, DOI:10.32604/fhmt.2025.066997 - 31 December 2025

Abstract The energy consumption of a Split air conditioning unit (ACU) inside a building is extremely large, and efforts to decrease this issue are ongoing. The current work aims to experimentally investigate the thermal performance of ACU using an external cooling-water loop for pre-cooling the condenser to improve the efficiency and to reduce energy consumption by reducing refrigerant temperature before entering the condenser, thereby reducing the coefficient of performance. The experiments are performed on ACU with and without using an external cooling-water loop under different climate conditions. By using the experimental data, the systems’ performances for… More >

Hind Abdulrahman Mahmood, Ameer Abed Jaddoa^*, Mohammed K. Al-Saadi

Frontiers in Heat and Mass Transfer, Vol.23, No.4, pp. 1281-1302, 2025, DOI:10.32604/fhmt.2025.066075 - 29 August 2025

Abstract Thermoelectric air conditioning systems based on the Peltier effect had two modes: heating and cooling. In this work, the proposed design provides continuous improvement in COP from the first minute of operation. In cooling mode, the coefficient of performance (COP) was 1.176 due to the techniques used in this device, and it increased to 1.24 in the last minute of operation. Concerning the steady-state scenario, from the first minute, the Q_c was larger than the W for the entire duration of the operation. The output temperature reaches 18.97°C, and the temperature on the cold side reaches… More >

Alya Penta Agharid¹, Indra Permana², Linlan Chang¹, Yi-Han Luo², Fujen Wang^2,*

Energy Engineering, Vol.122, No.9, pp. 3839-3866, 2025, DOI:10.32604/ee.2025.068586 - 26 August 2025

Abstract Air conditioning (AC) is essential for maintaining indoor comfort during Taiwan’s hot and humid summers but significantly contributes to increased energy consumption. This study evaluates the effects of AC duty-cycling strategies on energy performance, thermal comfort, and operational costs in office environments. Duty-cycling was implemented using a building energy management system (BEMS), which remotely controlled the ON/OFF cycles of AC units. Five duty-cycling modes were tested, with some modes incorporating air circulation during OFF periods. Field measurements of energy consumption, temperature, humidity, and air velocity were conducted and integrated with thermal comfort analysis tools to… More >

Yiming Rongyang¹, Chengyu Ji¹, Xiangdong Ding^2,*, Jun Gao¹, Jianjian Wei^2,3

Frontiers in Heat and Mass Transfer, Vol.23, No.2, pp. 685-701, 2025, DOI:10.32604/fhmt.2025.063785 - 25 April 2025

Abstract The effect of gradient exhaust strategy and blind plate installation on the inhibition of backflow and thermal stratification in data center cabinets is systematically investigated in this study through numerical methods. The validated Re-Normalization Group (RNG) k-ε turbulence model was used to analyze airflow patterns within cabinet structures equipped with backplane air conditioning. Key findings reveal that server-generated thermal plumes induce hot air accumulation at the cabinet apex, creating a 0.8°C temperature elevation at the top server’s inlet compared to the ideal situation (23°C). Strategic increases in backplane fan exhaust airflow rates reduce server 1’s inlet… More >

Linlan Chang¹, Win-Jet Luo^1,2, Indra Permana², Bowo Yuli Prasetyo³, Alya Penta Agharid¹, Fujen Wang^2,*

Energy Engineering, Vol.122, No.5, pp. 1771-1787, 2025, DOI:10.32604/ee.2025.062209 - 25 April 2025

Abstract Heating, Ventilation, and Air Conditioning (HVAC) systems are critical for maintaining thermal comfort in office environments which also crucial for occupant well-being and productivity. This study investigates the impact of integrating ceiling fans with higher air conditioning setpoints on thermal comfort and energy efficiency in office environments. Field measurements and questionnaire surveys were conducted to evaluate thermal comfort and energy-saving potential under varying conditions. Results show that increasing the AC setpoint from 25°C to 27°C, combined with ceiling fan operation, reduced power consumption by 10%, achieving significant energy savings. Survey data confirmed that 85% of… More >

Karam H. Mohammed¹, Ashraf E. Al-Mirani¹, Bashar Mahmood Ali², Omar Rafae Alomar^1,*

Frontiers in Heat and Mass Transfer, Vol.22, No.3, pp. 839-854, 2024, DOI:10.32604/fhmt.2024.052671 - 11 July 2024

Abstract This work involves an experimental study on the performance of automobile air-conditioning systems by adding Al₂O₃ nanoparticles to oil compressors to investigate their impacts on the enhancement of the speed cooling of refrigeration systems and to compare it with the system operated using only oil. The Al₂O₃ nanoparticles have been added to the oil compressor for different ranges of mass concentration (Ø = 0.1%, Ø = 0.15% and Ø = 0.2%). The stability of Al₂O₃ nanoparticles has been tested by direct observation for different time periods. The results indicated that the air conditioning system that operated by More >

Ali Jaber Abdulhamed^1,*, Aws Al-Akam¹, Ahmed A. Abduljabbar², Mohammed H. Alkhafaji³

Energy Engineering, Vol.120, No.8, pp. 1729-1746, 2023, DOI:10.32604/ee.2023.029069 - 05 June 2023

Abstract Thermoelectric generators (TEGs) are considered promising devices for waste heat recovery from various systems. The Seebeck effect can be utilized to generate power using the residual heat emitted by the filter dryer receiver (FDR) of an air conditioning (A/C) system, which would otherwise go to waste. The study aims to build a set of thermoelectric generators (TEG) to collect the waste heat of the FDR and generate low-power electricity. A novel electrical circuit with two transformers is designed and fabricated to produce a more stable voltage for operation and charging. The thermoelectric generator (TEGs) was… More >

Ghaith Yahya Abusaibaa^a , Kamaruzzaman Sopian^a,*, Hasila Jarimi^a , Adnan Ibrahim^a, Saffa Riffat^b

Frontiers in Heat and Mass Transfer, Vol.20, pp. 1-6, 2023, DOI:10.5098/hmt.20.21

Abstract This study will demonstrate the performance of a photovoltaic (PV) powered vapour compression cooling system connected to a Phase Change Material (PCM) storage tank. Three options were studied, namely (a) PV vapour compression with a PCM storage tank and an air-conditioned room with chilled water circulation with transparent membrane/desiccant; (b) PV vapour compression with a PCM storage tank and an air-conditioned room with chilled air dehumidification; and (c) PV vapour compression with a PCM storage tank and an air-conditioned room chilled by combined water circulation, a transparent membrane/desiccant, and air duct dehumidification. Simulation using TRNSYS,… More >

Peter van den Engel^1,*, Michael Malin², Nikhilesh Kodur Venkatesh¹, Luigi Antonio de Araujo Passos¹

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.3, pp. 783-805, 2023, DOI:10.32604/fdmp.2022.021962 - 29 September 2022

Abstract This research evaluates the performance of a Phase Change Material (PCM) battery integrated into the climate system of a new transparent meeting center. The main research questions are: a. “Can the performance of the battery be calculated?” and b. “Can the battery reduce the heating and cooling energy demand in a significant way?” The first question is answered in this document. In order to be able to answer the second question, especially the way the heat loading in winter should be improved, then more research is necessary. In addition to the thermal battery, which consists… More > Graphic Abstract

Wenwei Li¹, Xinjie Zhan^2,*, Baotian Wang¹, Jinyu Zuo¹

Journal of Renewable Materials, Vol.11, No.1, pp. 363-378, 2023, DOI:10.32604/jrm.2022.022254 - 10 August 2022

Abstract Municipal sludge is a sedimentation waste produced during the wastewater process in sewage treatment plants. Among recent studies, pilot and field tests showed that chemical conditioning combined with vacuum preloading can effectively treat municipal sludge. To further understand the drainage and consolidation characteristics of the conditioning sludge during vacuum preloading, a large deformation nonlinear numerical simulation model based on the equal strain condition was developed to simulate and analyze the pilot and field tests, whereas the simulation results were not satisfactory. The results of the numerical analysis of the pilot test showed that the predicted… More >