D. Banu

Investigation of the Thermal Performance of a Passive Solar Test-Room with Wall Latent Heat Storage

Abstract An experimental and numerical simulation study is presented of the application of phase change materials (PCM) in building envelope components for thermal storage in a passive solar test-room. Gypsum board impregnated with a phase change material was used. The experimental study was conducted in a full-scale outdoor test-room with the PCM gypsum board as inside wall lining. An explicit finite difference model was developed to simulate the transient heat transfer process in the walls. Reasonable agreement between the simulation and the experimental results was observed. It was shown that the utilization of PCM gypsum board in a passive solar building may reduce the maximum room temperature by about 4 °C during the daytime and can reduce the heating load at night significantly.

Latent heat storage in building materials

Abstract Thermal storage is an important aspect of energy conservation which is greatly assisted by the incorporation of latent heat storage in building products. This can be achieved by the use of various phase change materials (PCMs) which absorb and release heat much more effectively than conventional building materials. Different types of PCMs and their characteristics are described. The performances of gypsum wallboard and concrete block which have been impregnated with PCMs are examined. Manufacturing techniques are considered and applications of PCM wallboard and PCM concrete block are discussed.

Development and application of organic phase change mixtures in thermal storage gypsum wallboard

Abstract A latent heat storage material which would be useful in hot climate is proposed. It is a mixture of 93–95 wt% commercial Methyl Palmitate (MeP) with 7-5 wt% commercial Methyl Stearate (MeS), having a melting-freezing interval of approximately 23–26.5°C and a latent heat of transition of at least 180 kJ/kg. Normal wallboard may be impregnated with up to 25 wt% of one of these mixtures. Air passing over such an impregnated wallboard would be cooled down due to the heat absorption taking place between 23–26.5°C when the mixture melts. Recharging the wallboard will occur at 22–23°C during freezing, when the latent stored heat is released to the cool night air. The total storage capacity of such an impregnated wallboard, in a 3.5°C temperature interval, is at least twelve times higher than the storage capacity of wallboard alone over this range.

Obtaining an energy storing building material by direct incorporation of an organic phase change material in gypsum wallboard

Abstract A laboratory scale energy storage gypsum wallboard was produced by the direct incorporation of 21%–22% commercial grade butyl stearate (BS) at the mixing stage of conventional gypsum board production. The incorporation of BS was strongly facilitated by the presence and type of small amounts of dispersing agents. The physico-mechanical properties of the laboratory-produced thermal storage wallboard compare quite well with values obtained for standard gypsum board. The energy storing board has a ten-fold increase in capacity for the storage and discharge of heat when compared with gypsum wallboard alone.

Latent heat storage in concrete

Abstract Sensible heat storage in building materials has been practiced for thousands of years. Recent work at the Centre for Building Studies in the impregnation of concrete with various phase change materials (PCMs) has resulted in the addition of latent heat values which can increase its total thermal storage capacity in the range of 100%–130% within the thermal comfort zone. The alkaline nature of concrete makes it unsuitable for use with many PCMs so the choice of an appropriate impregnant is important. Three PCMs were selected and tested: butyl stearate, dodecanol and polyethylene glycol 600. All three were found to be compatible with autoclaved concrete block which as a low alkalinity. In addition, dodecanol was also found to be suitable for use in regular concrete block.

Control aspects of latent heat storage and recovery in concrete

Abstract This paper presents the results of macro scale tests that compare the thermal storage performance of ordinary concrete blocks with those that have been impregnated with two phase change materials (PCM). One is a commercial Butyl Stearate (Emerest 2326), and the other is a commercial Paraffin (Unicere 55). The comparative characteristics of these PCM – concrete combinations were examined. Also, the effect of air velocity was studied in respect to the control of the rates of heat storage and discharge. This research is an extension of the laboratory scale work in this area, which were carried out in recent years.

Full scale thermal testing of latent heat storage in wallboard

Abstract Full scale thermal storage tests were conducted in a room lined with PCM wallboard having latent heat storage capacity. The results were compared with those obtained from tests conducted in a similar room lined with ordinary wallboard. The research showed that PCM wallboard can function efficiently as a thermal storage medium which can be applied to peak load shifting, improved use of waste and solar heat as well as more efficient operation of heating and cooling equipment.

Low chain esters of stearic acid as phase change materials for thermal energy storage in buildings

Abstract Esterification of different commercial mixtures of stearic and palmitic acid with methyl, butyl and propyl alcohols was undertaken at the laboratory scale and the thermal properties of the esters were determined by Differential Scanning Calorimetry (DSC). Twelve products were obtained with melting points in the interval of 17–34°C and freezing points in the range of 20–32°C. About half of them are characterized by a latent heat of transition of 140–150 J/g and the other half by a latent heat of transition of 180–190 J/g. Even at the incipient phase, research concerning the esterification of different commercial grades of stearic acid has demonstrated the ability to tailor PCMs with specific transition temperature.

The stability of phase change materials in concrete

Abstract The heat storage capacity of concrete building products can be greatly increased by impregnanting the concrete with phase change materials (PCMs). A very important consideration in the manufacture and use of these thermal storage building products is the stability the PCM in the concrete throughout its service life. The use of modified concrete was developed to increase this stability. This technique and the development of improved means of incorporating various kinds of PCM in several types of concrete, resulted in stable PCM concrete products which had good thermal storage characteristics.

Contribution to the study of rigid PVC polyblends with different lignins

Evaluation of different types of lignins and lignin derivatives, representing a spectrum of significant differences in regard to delignification processes and the nature of wood, in blending with a rigid poly(vinyl chloride) (PVC) compound for outdoor application is discussed. The influence of lignins on the processability of the blends, as well as on their strength at yield, break, and impact before weathering, and after 7 days of artificial weathering period (in the presence of ultraviolet light, humidity, and moderate temperature) was investigated, and the data correlated with those of rigid PVC compound. Infrared and thermal analysis were performed to elucidate the morphology of the blends.