Wei Tian^a , Mingjun Pang^a,*, Na Xu^b,†

Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-12, 2021, DOI:10.5098/hmt.16.13

Abstract Drag reduction (DR) by the additive of mixed surfactant and polymer is investigated in detail in a rotating disk apparatus (RDA). Polyethylene oxide (PEO) and Cetyltrimethyl ammonium chloride (CTAC)/sodium salicylate (NaSal) are chosen as polymer and surfactant, respectively. It is investigated on the influence of combination concentration of polymer & surfactant, temperature and Reynolds number on the drag-reducing rate. The present experimental results show that the drag-reducing rate of the mixed solution is definitely higher than that of the pure PEO or CTAC/NaSal solutions. This phenomenon is especially sharp at the high temperature and/or the large Reynolds number. When the… More >

Hussien Aziz Sahe^b,*, Ala'a Abbas Mahdi, Qusay Rasheed Al-amir

Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-15, 2021, DOI:10.5098/hmt.16.9

Abstract In this study, indoor air quality and thermal comfort were investigated for two persons sitting inside an office room of dimensions (3×2.5×2.5m). The office room is equipped with personal ventilation systems positioned 50 cm from the person's face. These systems are characterized by the ability to change the rates of airflow (ATD). Experimental studies and results were conducted on a thermal manikin that simulates the human body in a sitting position, and the results are compared with CFD analysis using the k-epsilon and the RNG turbulent models. The experimental study focused on measuring the speed and temperature of the air… More >

V. W. Bhatkar^a,*, Anirban Sur^b,*

Frontiers in Heat and Mass Transfer, Vol.17, pp. 1-5, 2021, DOI:10.5098/hmt.17.12

Abstract A jet pump or an ejector uses primary fluid flow as motive fluid to entrained secondary fluid. In this paper, the main intention is to find suction flow rate, primary flow rate, secondary flow rate, loss factors and ejector efficiency for an applied pressure. The values of the different loss factors estimated are primary nozzle loss factor (Kp)=0.06, suction loss factor (Ks)=0.04-0.1, mixing loss factor (Km)=0.07-0.1 and diffuser loss factor (Kd)=0.0289. It is found that with the increase in pressure across the ejector, efficiency increases with increase in flow ratio and decrease in pressure ratio. More >

Kai Zhu¹, Hao Chen^1,*, Shuang Wang^1,*, Chuan Yuan^1,2, Bin Cao³, Jun Ni¹, Lujiang Xu⁴, Anqing Zheng⁵, Arman Amani Babadi¹

Journal of Renewable Materials, Vol.11, No.6, pp. 2849-2864, 2023, DOI:10.32604/jrm.2023.026317

Abstract Microalgae biomass is an ideal precursor to prepare renewable carbon materials, which has broad application. The bioaccumulation efficiency (lipids, proteins, carbohydrates) and biomass productivity of microalgae are influenced by spectroscopy during the culture process. In this study, a bilayer plate-type photobioreactor was designed to cultivate Chlorella protothecoides with spectral selectivity by nanofluids. Compared to culture without spectral selectivity, the spectral selectivity of Ag/CoSO₄ nanofluids increased microalgae biomass by 5.76%, and the spectral selectivity of CoSO₄ solution increased by 17.14%. In addition, the spectral selectivity of Ag/CoSO₄ nanofluids was more conducive to the accumulation of nutrients (29.46% lipids, 50.66% proteins, and… More > Graphic Abstract

Zahra F. Hussain^a,*, Ahmed J. Hamed^b, Abdul Hadi N. Khalifa^b, Mohanad F. Hassan^b, Fawaz A.Najim^c,†

Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-11, 2022, DOI:10.5098/hmt.18.14

Abstract At places far from the energy grid lines, freshwater is sometimes needed. Consequently, even countries with rich energy resources, such as the Arabian Gulf countries, have shown strong interest in desalination processes that often use renewable energy sources. In the present work, a desalination unit depending on the humidification-dehumidification principles is fabricated and tested under Baghdad, Iraq conditions. The HDH system under study consists of 6 parabolic trough solar collectors (PTSC) of a total aperture area of 8.772 m2 , the humidifier, and the dehumidifier and a tracking system. The effects of salty water flow rate and the HDH air-water… More >

Marwa M. Ibrahim^a,*, Amal El Berry^a, Karim Ashour^b

Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-11, 2022, DOI:10.5098/hmt.18.9

Abstract Conventional sources of energy are rapidly decreasing more and more. Hence, Renewable energy is presently attracting significant. Therefore, this paper aims at investigating the techno-economic feasibility of SWHS for swimming pools in tourist hotels and resorts. The proposed system presents an active direct system without auxiliary heaters to evaluate the potential for using solar thermal collectors for heating swimming pools of tourist resort; installed in El Gouna city, Egypt, and to size solar collector using TSOL simulation software package to meet the demand of hot water, to analyze the impact of collector design-parameters concerning system cost, system yield and economic… More >

Hawraa T. Gatea^a , Atheer S. Hasson^a, Adil A. Alwan^b, Mohammed Y. Jabbar^b, Azher M. Abed^a

Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-6, 2022, DOI:10.5098/hmt.18.5

Abstract The present work is an experimental study into the thermal performance of air conditioning system (split unit), bases on using renewable energy as an assisted facter. The serpentine tube flat plate solar collector (STFPSC) is combined with 1-ton capacity split air conditioning system, which is installed after the compressor to superheat the refrigerant that leaves the compressor. The conventional air conditioning (A/C) system is compared with the suggested system. The results show that the coefficient of performance (COP) of the solar assisted air conditioning system (SAAC), is affected by the enhancement of the solar collector, which enrolls the effect of… More >

Yun Hao^* , Shaohua Lv, Song Wu

Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-8, 2022, DOI:10.5098/hmt.18.3

Abstract Traditional methods of enhancing the thermal efficiency of heating furnaces in continuously producing oilfields, such as replacing existing units with more efficient units or renovating old furnaces, are highly inconvenient. This paper studied on the characteristics of nanofluids, a novel heat transfer medium with excellent heat transfer characteristics to enhance the thermal efficiency of heating furnaces. The stable nanofluids (Al₂O₃-H₂O, SiO₂- H₂O, and TiO₂-H₂O) were prepared by a two-step method and various chemical and physical treatments were carried out. Thermal conductivities of the nanofluids were measured using the transient hot-wire method. Based on the analysis, the most appropriate nanofluid (TiO₂-H₂O)… More >

Nagham Yass Khudair^a,*, Ahmed Kadhim Hussein^b

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-6, 2022, DOI:10.5098/hmt.19.29

Abstract There has been a shift in our concern for energy towards renewable energy sources as a result of the increasing demand for energy and the decreasing supply of fossil fuels. Solar energy is, without a shadow of a doubt, the most environmentally friendly and beneficial alternative among all of the other sources that are now available. In today's world, many people harvest energy from the sun using a variety of various kinds of solar collectors. It has been discovered that the efficiency of the solar collector is reliant on the properties of the working fluid, which is responsible for the… More >

Aparna Kottapallia , Ramakrishna Konijeti^b,*

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-11, 2022, DOI:10.5098/hmt.19.11

Abstract Scroll technology is widely used in refrigerators as compressors. This research paper presents the performance of a scroll-type expander derived from a scroll compressor. The research is carried out at low pressures. The effect of mechanical load on performance has been evaluated using compressed air as a working fluid. Two stages of the evaluation process are carried out in this research. In the first stage, the scroll expander model is numerically simulated using the CFD approach to predict the factors influencing the scroll expander performance. In the later stage, an experiment is carried out on a scroll-type expander prototype developed… More >