International Conference on Mechanical, Industrial and Energy Engineering 2020 19-21 December, 2020, Khulna, BANGLADESH * Corresponding author. Tel.: +88-01786146785 E-mail addresses: anikarahman6623@gmail.com ICMIEE20-089 Numerical investigation on the thermal performance of a hospital ward roof incorporating phase change material (PCM) Anika Rahman Riya 1,* Rafe Md. Abu Zayed 2 , Sumaiya Saima Sharmi 3 1 Department of Materials and Metallurgical Engineering, Bangladesh University of Engineering and Technology 2 Department of Mechanical Engineering, Bangladesh University of Engineering and Technology 3 MBBS, Patuakhali Medical College ABSTRACT Overheating is a common phenomenon in a tropical country like Bangladesh. So, ensuring the thermal comfort of hospital patients is necessary for proper health treatment. But in Bangladesh, the thermal comfort of the patient is compromised as installation of the air conditioning system in every general ward of the hospital is impossible due to economic constraints. So, a cheap but effective solution is badly needed to cope with this situation. In that case, PCM (phase change materials) can be an alternative to improve the thermal condition and reduce temperature fluctuation in hospitals in Bangladesh. Phase changing ability at a constant temperature and latent heat storage property of PCM have been proved very effective for the improvement of building thermal condition over the years. In this study, the improvement of thermal condition of the general ward of Patuakhali Medical College (PkMC) is analyzed using PCM as a retrofitting option. A numerical simulation work is performed to analyze and compare the effect of three different PCMs on the enhancement of thermal comfort hours. Finally, based on the result, the best PCM is chosen for optimum thermal management. Keywords: Hospital general ward, Thermal comfort, Phase change material, Numerical simulation. 1. Introduction Over the last few years the demand for air conditioning has greatly increased in Bangladesh resulting in increased energy consumption. In public health sector, hospital is one of the most energy consuming areas which lacks facilities for thermal comfort due to economic constraints. For this reason, ensuring thermal comfort of patients and searching for more energy efficient building model have become important criteria for Bangladesh nowadays. The use of thermal energy storage has a great importance in this regard as it can control the daily temperature fluctuation and decrease the energy demand for heating and cooling. As a latent heat TES(thermal energy storage) system there are several research going on in the application of phase changing materials (PCM) [1] which can store 5-15 times more heat per unit volume than sensible heat storage materials(rock, water, masonry). Researches have been conducted for over two decades to find potential PCM in residential building heat comfort applications. Cabeza et al.[2] reviewed the categories of PCM (organic, inorganic, eutectics) with their most possible problems or solutions during application in building and found two PCM-based TES systems. Among them, active systems require an additional fluid loop to charge or discharge a storage tank but passive systems don’t require that heat exchanger and store energy in the form of latent heat. There are also several studies on the incorporation of PCM in roof, wall, floor, window glazing by using micro or macro encapsulation. Cabeza et al. [3] discussed the effectiveness of using microencapsulated PCM within concrete wall to control building temperature and how it can help to minimize the temperature fluctuations. There was 1.15°C reduction in room temperature during winter while using PCM wallboard [4]. In another study, Alqallaf et al. [5] used PCM containing cylindrical holes in roof which causes maximum reduction in heat flux of about 17.26%. Pasupathy and Velraj also discussed how integration of PCM on the roof could narrow down the indoor air temperature swings [6]. Ismail and Henriquez [7] gave a different idea of incorporating a moving curtain of PCM for thermally effective windows. Barzin et al. [8] proposed an experimental investigation by comparing two small room. The first room was comprised of ordinary gypsum board while the second one included PCM (paraffin) boards on the floor. In another experiment, A.G. Entrop et al.[9] discussed the method of storing thermal energy by using PCM layer in concrete floor and how this energy can be utilized to ensure thermal comfort. Again another study revealed a new kind of underfloor electric heating system with shape-stabilized phase change material (PCM) plates [10]. Besides these experimental studies, there are few studies on the use of PCM in tropical climate area. Pasupathy et al. [11] performed a study where PCM is used in roof in tropical climate. But in tropical climate like Bangladesh, there is still less work on PCM to maintain thermal comfort in buildings, especially in health sector. This study aims at analyzing the feasibility of using PCM to improve thermal condition in hospital general wards of Bangladesh. A numerical simulation work is performed to analyze and compare the effect of three different PCMs on thermal comfort of the patients of Patuakhali Medical College, Bangladesh (PkMC) hospital general ward. Based on the simulation result, PCM with the best thermal performance is suggested. 2.Modelling of PCM embedded hospital roof system The dimension of the roof of PkMC is taken for modelling purpose. A composite roof comprised of PCM