Abstract
A phase change material (PCM) has the characteristics of latent heat storage, controllable phase transition temperature (PTT), and chemical stability. It can naturally regulate the ambient temperature in a certain range and reduce the load of air conditioning operation. Therefore, it plays an important role in the field of energy-saving buildings, and the PTT of PCM is one of the decisive factors. In this paper, through analyzing PCM installed in solar buildings at various regions, a binary eutectic mixture (EM) was prepared from lauric acid (LA) and octadecanol (OD) by the method of mixed melting, and the PTT and enthalpy of the EM were 39.87 °C and 186.94 J/g, respectively. The PTT, latent heat, and EM ratio were determined by theoretical calculation, the step cooling curve, and DSC. FT-IR result shows that no chemical reaction occurs among the components of composites, and the molecular forces are uniform and stable. XRD results further proves that no other phases existed in the composites. Thermal cycles (500) and the TG test show that the EM has excellent thermal stability and heat resistance, which meets the engineering application. Due to the thermodynamic properties of the EM, it can be used in thermal cooling of electronic systems, building envelopes, and thermal storage in solar buildings to obtain a good energy-saving effect.
Highlights
IntroductionWith the sustainable development of society, building energy consumption accounts for about 35% of the total national one, and more than 50% of it comes from air conditioning and heating.[1,2] As special heat storage materials, a phase change material (PCM) controlling the ambient temperature by absorbing and releasing the heat to the surrounding is a new green material to reduce building energy consumption.[3−5] PCM in solar buildings improves the heat storage of the building envelope effectively and cuts down the load of air conditioning or heating, which is a technology worthy of great research and promotion.[6−9]For PCM in the current building structure, the phase transition temperature (PTT) is usually required to be around 20−40 °C and more rigorous in specific climatic conditions and building environments.[10−13] The optimal PTT of PCM in buildings is related to the climate, season, and application purpose of the building, especially in solar buildings.[14,15] Thermal regulation measures for passive solar buildings combined with a PCM wall in different seasons in North China were proposed by Chen;[16] the PTT of the PCM is about 20 °C, and it is feasible at other similar climate areas
Thermal regulation measures for passive solar buildings combined with a phase change material (PCM) wall in different seasons in North China were proposed by Chen;[16] the phase transition temperature (PTT) of the PCM is about 20 °C, and it is feasible at other similar climate areas
The preparation process of the eutectic mixture (EM) is concise, and the PTT of EM reduces that of a single one, which broadens the application scope, and a new choice is provided for building energy-saving materials
Summary
With the sustainable development of society, building energy consumption accounts for about 35% of the total national one, and more than 50% of it comes from air conditioning and heating.[1,2] As special heat storage materials, a PCM controlling the ambient temperature by absorbing and releasing the heat to the surrounding is a new green material to reduce building energy consumption.[3−5] PCM in solar buildings improves the heat storage of the building envelope effectively and cuts down the load of air conditioning or heating, which is a technology worthy of great research and promotion.[6−9]For PCM in the current building structure, the PTT is usually required to be around 20−40 °C and more rigorous in specific climatic conditions and building environments.[10−13] The optimal PTT of PCM in buildings is related to the climate, season, and application purpose of the building, especially in solar buildings.[14,15] Thermal regulation measures for passive solar buildings combined with a PCM wall in different seasons in North China were proposed by Chen;[16] the PTT of the PCM is about 20 °C, and it is feasible at other similar climate areas. Peippo et al.[18] studied the thermal performance of passive solar houses in different areas of the US and concluded that the PTT of PCM should be 1−3 °C higher than the indoor average temperature. Wang[21] studied the energysaving effect of solar ventilation and the phase change heat storage wall in buildings in South China, in the daytime of transition season, and the maximum temperature of the outer surface wall is about 40 °C, the higher PTT of PCM should be considered. Chen et al.[22] introduced a new type of phase change energy storage wallboard, and the energy-saving rate in the heating season can reach 17% or even higher. In the field of building thermal storage and thermal cooling of electronic systems, many scholars have done a lot of Received: July 9, 2021
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