Preparation of cement mortar wall incorporated with coconut oilparaffin eutectic phase change materials (PCM) for buildings passive cooling applications

Rosman Rizal, Muhammad Mustaqim (2023) Preparation of cement mortar wall incorporated with coconut oilparaffin eutectic phase change materials (PCM) for buildings passive cooling applications. Project Report. Melaka, Malaysia, Universiti Teknikal Malaysia Melaka. (Submitted)

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Abstract

Compressor-driven air conditioning systems are most popular methods to meet the ever increasing demand for cooling in buildings sectors. The obvious drawback of these air- conditioning devices is the high electrical energy consumption. Building sectors in Malaysia consume almost 14.3% of total energy, with residential and commercial buildings accounting for 53% of total energy consumption. To produce electricity, power generation stations require to use coal or gas as it combustion sources. This releases particularly CO2 gas to atmosphere and contribute to global warming. Another detrimental consequences of utilizing conventional vapour-compression refrigeration systems is the high ozone deplection potential (ODP) posses by the refrigerant used as working fluids in the systems particularly when the refrigerant leak to atmosphere. Therefore, it is important to develop new energy-efficient technologies in buildings sector for air-conditioning applications. For example, incorporation of phase change material (PCM) into building materials could increase the thermal inertia of buildings thus provide thermal comfort for the occupants and reduce the electric energy consumption. PCM utilized the night temperature swing to absorb heat from the inner space of a buildings when the temperature rise above the PCM melting temperature. During this phase change process, PCM melts. At night when the surroundings temperature drops, the PCM solidify back to its solid state. Therefore, PCM-incorporated buildings materials could be utilized as a mean of passive cooling of buildings in hot climates. The main purpose of this study is to prepare macroencapsulated PCM that can be incorporated into cement mortar wall. The eutectic PCM is prepared by mixing paraffin and coconut oil at various mixing ratio to obtain the optimal mixing ratio that suit the thermal comfort temperature at 260C~280C. Both coconut oil and paraffin are organic PCM that most compatible with buildings materials. The optimum eutectic PCM is of mixing ratio 95% coconut oil and 5% paraffin wax, with a melting point of 280C. Adding more coconut oil and reducing paraffin wax mass resulted in lower melting points. However, this temperature range is not suit with Malaysia climate in particularly. The PCM applications are hindered by the low thermal conductivity of the PCM-incorporated building materials. To optimize heat transfer via enhancement of thermal conductivity, the shell for the macroencapsulated PCM were made of two different materials i.e., clay and aluminium ring. The thermal performance of the PCM-incorporated cement mortar wall was investigated using a reduced-scale test room, outdoor test and night to days simulation test. Based on the reduced- scale thermal test, the aluminium ring MPCM incorporated with mortar achieves a stable temperature in the approximately of 310C on the mortar wall surface when exposed to 350C. Increasing the quantity mass of PCM resulted in 1.30C lower mortar wall surface temperature. The cubicle PCM mortar show the ability to act efficiently as a latent and sensible thermal energy storage. The outdoor test show the temperature cubicle mortar with PCM increased slowly to 39.90C when directly exposed to sunlight for 3 hours where as cubicle mortar without PCM was 41.80C. The temperature different is 20C with 450C of surrounding temperature. The day to night simulation test for the thermal performance of the PCM mortar. The cubicle mortar with PCM can stabilize indoor temperature at 270C after 30 minutes with 250C surrounding temperature. The cubicle mortar without PCM only maintain the same indoor temperature only for 5 minutes. The situations shows that cement mortar incorporated with PCM are reducing the indoor temperature fluctuation and can increase thermal mass in buildings via la tent and sensible heat transfer.

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