International Journal of Heat and Mass Transfer 150 (2020) 119311 Contents lists available at ScienceDirect International Journal of Heat and Mass Transfer journal homepage: www.elsevier.com/locate/hmt Technical Note The enhancement of spray cooling at very high initial temperature by using dextrose added water L. Das a , A.R. Pati a , Anita Panda a , B. Munshi a , D.K. Sahoo b , K. Barik c , S.S. Mohapatra a,∗ , A. Sahoo a a Department of Chemical Engineering, National Institute of Technology Rourkela, Rourkela 769008, India b Department of Metallurgical and Materials Engineering, National Institute of Technology Rourkela, Rourkela 769008, India c Department of Chemical Engineering, Indira Gandhi Institute of Technology, Sarang 759146, India a r t i c l e i n f o Article history: Received 6 May 2019 Revised 2 January 2020 Accepted 3 January 2020 Available online 10 January 2020 Keywords: Dextrose Exothermic Dissolution Morphology a b s t r a c t In the current work, by decreasing the sensible heat extraction period and enhancing the internal energy of the evaporating droplet; the high mass flux spray cooling is enhanced with the additional advantages such as attainment of unaltered surface morphology and zero deposition of the additives on the evapo- rating surface. To achieve the above-mentioned requirements, dextrose is used as an additive in water, which decreases coolant temperature due to heat of dissolution. Furthermore, the exothermic reaction between aqueous glucose and oxygen fulfill the latter requirement. In the current work, the heat transfer analysis clearly depicts enhancement with respect to the heat removal rate obtained in case of cooling by pure water. In addition to the above, the post quenching surface analysis of the heat-treated steel plate assures unaltered surface morphology. The comparison of the current quenching process with the cooling processes reported in the literature clearly asserts its suitability for the fast quenching operation. © 2020 Elsevier Ltd. All rights reserved. 1. Introduction The rapid industrialization leads to an upsurge in demand of steel by various industries such as railway locomotive, automobiles, heavy and light machines, construction etc. The most important factors which account for the widespread use of steel are their mechanical properties [1–3]. These properties include an amalga- mation of high tensile strength with good weldability and afore- said characteristics depend on the quenching rate at ROT. The high cooling rate can be achieved through spray cooling by using vari- ous additives plus water as a coolant [4–8]. The presence of additives in the water alters the thermo- physical properties of the coolant, surface properties of the hot plate and alteration of heat transfer mechanism in the favourable direction of heat transfer. Therefore, high heat transfer rate results. In this regard, various pioneered work is available in open liter- ature. The first generation researcher of cooling technology used single additive to enhance the heat removal rate at very high tem- perature [9,10]. In this regard, Pati et al. [11] reported that in the case of salt added water spray cooling, the achieved critical flux is 1.6 times higher as compared to pure water. Furthermore, In the ∗ Corresponding author. E-mail address: mohapatras@nitrkl.ac.in (S.S. Mohapatra). follow up research, Liu et al. [12] used the mixture of ethanol- water mixture as a coolant and observed the augmentation in heat transfer rate. Pati et al. [13] further extended the work reported by Liu et al. [12] for both upward and downward facing spray by us- ing ethanol as additives. The investigators found that the enhanced critical heat flux (2.57 MW/m 2 ) in case of upward facing spray by using ethanol-water mixture as a coolant. From the literature, it is revealed that the use of aforesaid additives creates enhance- ment at the expenses of the various disadvantages such as failure in the attainment of uniformity in temperature distribution and unaltered surface morphology [14]. Therefore, to avoid the above- discussed disadvantages, Bhatt et al. [15] tried to enhance the heat removal rate without using additives. They considered hot water as a coolant and achieved augmentation in the case of spray cooling by hot water. However, the degree of enhancement is sufficient to mitigate the requirements of the high heat applications. In the current work, as shown in Fig. 1, the sensible heat ex- traction period is tried to minimize by creating heat of dissolu- tion followed by exothermic reaction during evaporation. The con- ditions for the exothermic reactions are 98 °C and 1 atm. As these conditions are observed in the spray evaporative type of cooling techniques, reactions are expected to occur during evaporation. In the current work, the entire heat transfer tenure is divided into two parts: (1) Sensible heat extraction period and (2) Latent heat extraction period. Heat extracted in latent heat form is many https://doi.org/10.1016/j.ijheatmasstransfer.2020.119311 0017-9310/© 2020 Elsevier Ltd. All rights reserved.