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Plastic materials can absorb moisture from the atmosphere even after drying. This absorbed moisture can cause many defects in the molding process. Conventionally, a dryer is used to reduce the moisture content. However, the use of a drying unit involves huge daily power consumption and is also time-consuming. Therefore, this study proposed a new method to reduce the impact of moisture on molded product part quality through the optimization of plasticization parameters while reducing drying time. Two plastic materials, polyurethane (TPU) and polycarbonate (PC), were used for the experimental verification. Key plasticization parameters, including back pressure, screw rotation speed, and barrel temperature were chosen; their influence was investigated by the design of experiments (DOE). Moisture-induced defects, such as air bubble area, part surface gloss, and appearance were measured and correlated with the plasticization parameters. It was found, after optimization via a three-level DOE and factorial design multivariate statistical analysis using TPU, that the gloss (GU) of the PC part without drying was very close to that (98.4 GU) of the fully dried PC. The proposed methodology may help molders to improve production efficiency and achieve cost savings. [ABSTRACT FROM AUTHOR]

In this paper, a series of experiments assessing the moisture buffer value (MBV) of four internal wall assembly samples made from hygroscopic materials was performed. A modified Nordtest protocol was used. Moisture buffer values of all the investigated wall assemblies, with varying moisture loads in the range of 50% to 80%, showed a moderate moisture buffer value (MBV: 0.5–1.0 (g·m−2·%RH−1)). The results showed that in a wall assembly where the MBV of the whole assembly is lower than the MBV of the outer layers, the moisture-buffering capacity of the inner layer is untapped. Outer layers affect inner layers by changing their moisture-buffering capacity, which in turn changes the overall performance of the whole assembly. In addition, it was observed that if the penetration depth value of the outer layer is greater than its thickness, vapour reaches into the deeper layer and wall assemblies made of layers with materials characterized by a lower value of penetration depth reach steady state more slowly. The WUFI Pro tool was used to compare the simulated and experimental results. Despite the discrepancies between these results, it offers a simplified method, helping designers make decisions about which materials to choose to improve the moisture-buffering effect. [ABSTRACT FROM AUTHOR]

The phase change of water from liquid to vapor is one of the most energy-intensive physical processes in nature, giving it immense potential for cooling. Diverse evaporative cooling strategies have resulted worldwide, including roof ponds and sprinklers, courtyard fountains, wind catchers with qanats, irrigated green roofs, and fan-assisted evaporative coolers. These methods all require water in bulk liquid form. The evaporation of moisture that has been sorbed from the atmosphere by hygroscopic materials is equally energy-intensive, however, yet has not been examined for its cooling potential. In arid and semi-arid climates, hygroscopic earth buildings occur widely and are known to maintain comfortable indoor temperatures, but evaporation of moisture from their walls and roofs has been regarded as unimportant since water scarcity limits irrigation and rainfall; instead, their cool interiors are attributed to well-established mass effects in delaying the transmission of sensible gains. Here, we investigate the cooling accomplished by daily cycles of moisture sorption and evaporation which, requiring only ambient humidity, we designate as "intrinsic" evaporative cooling. Connecting recent soil science to heat and moisture transport studies in building materials, we use soils, adobe, cob, unfired earth bricks, rammed earth, and limestone to reveal the effects of numerous parameters (temperature and relative humidity, material orientation, thickness, moisture retention properties, vapor diffusion resistance, and liquid transport properties) on the magnitude of intrinsic evaporative cooling and the stabilization of indoor relative humidity. We further synthesize these effects into concrete design guidance. Together, these results show that earth buildings in diverse climates have significant potential to cool themselves evaporatively through sorption of moisture from humid night air and evaporation during the following day's heat. This finding challenges the perception of limited evaporative cooling resources in arid climates and greatly expands the applicability of evaporative cooling in contemporary buildings to water-stressed regions. [ABSTRACT FROM AUTHOR]

Validated by a large-scale experimental investigation on moisture buffering (MB) effect, a whole building Heat, Air and Moisture (HAM) simulation tool, BSim, is applied to evaluate the impact of a number of parameters on the moisture buffering potential of a full-scale test room finished with hygroscopic materials. The Maximum Accumulated Moisture Buffering Value (MAMBV), developed from the moisture balance analyses in the experimental study, is used in the BSim simulation result analyses to evaluate the impact of various parameters. The parameters investigated include ventilation rates (0.5-5 ACH), types of materials (uncoated gypsum board, wood paneling, orientated strand board, aerated cellular concrete, and telephone book paper), humidity conditions of supply air, volume rates, and steady-state outdoor conditions. It is found that all these parameters have a significant impact on the moisture buffering potential except for the steady-state outdoor conditions. Two material properties, the moisture capacity and vapor permeability, determine the moisture buffering capacities of materials under different moisture generation regimes. [ABSTRACT FROM AUTHOR]

The energy demand for the air-conditioning of buildings has shown a very significant growth trend in the last two decades. In this paper three alternative hygroscopic materials for desiccant wheels are compared considering the operation of the air handling unit they are installed in. The analyses are performed by means of the TRNSYS 17® software, simulating the plant with the desiccant wheel made of: silica-gel, i.e., the filling actually used in the experimental plant desiccant wheel of the University of Sannio Laboratory; MIL101@GO-6 (MILGO), a composite material, consisting of graphite oxide dispersed in a MIL101 metal organic framework structure; Campanian Ignimbrite, a naturally occurring tuff, rich in phillipsite and chabazite zeolites, widespread in the Campania region, in Southern Italy. The air-conditioning system analyzed serves a university classroom located in Benevento, and it is activated by the thermal energy of a solar field for which three surfaces are considered: about 20, 27 and 34 m2. The results demonstrate that a primary energy saving of about 20%, 29%, 15% can be reached with silica-gel, MILGO and zeolite-rich tuff desiccant wheel based air handling units, respectively. [ABSTRACT FROM AUTHOR]