Experimental Studies of Moisture Transport in Grain Material and Individual Grain

The issue of moisture transfer in the total mass of the material and in a single grain is discussed taking into account the biological characteristics of the endosperm cells of the grain. Experimental studies of this process have been performed. The results of the oscillating mode with laying have been analyzed. It was found that during the time of laying, the moisture content of the grain shell increases significantly and the moisture content of the core decreases slightly, and during the implementation of the laying after the heating period, a larger amount of moisture moves from the core into the shell than after the cooling period.

Energy and Environmental Effects of Human Habits in Residential Buildings Due to COVID-19 Outbreak Scenarios in a Dwelling near Rome

The COVID-19 pandemic and resulting containment measures have shown that energy consumption in buildings is linked to several factors, such as living habits, occupancy profiles, and heating ventilation and air conditioning (HVAC) systems. This paper addresses the influences of such factors on energy consumption in a residential building, analysing different scenarios (pre-COVID-19, lockdown, post-COVID-19), in terms of discomfort and energy needs, through the new hourly calculation method (UNI EN ISO 52016). Energy and environmental effects were studied in a real case study near Rome by varying occupancy profiles, lighting and appliance schedules, and HVAC systems. Results show that, during the heating period, the lockdown scenario led to the lowest hours of discomfort (−29% on average), but the highest in the cooling period (up to +154%, +28% on average). The same scenario led to reasonable reduction of energy needs for heating (−14%), but also highlighted a significant increase (+60%) for the cooling period. This study underlines how the pandemic has influenced the energy and environmental behaviours in buildings. Moreover, the new hourly calculation method points out the importance of analysing HVAC systems, in terms of hours of discomfort, which could provide results that are more reliable.

Investigation of the envelope’s thermal transmittance influence on the energy efficiency of residential buildings under various Mediterranean region climates

Improving the energy efficiency of residential buildings is of outmost importance for reducing their environmental footprint. Recent studies demonstrate that a highly insulated building envelope may burden the building’s performance during the cooling period, especially in regions with hot summers. In this study, the energy performance of a residential building in different Mediterranean regions (Jordan, Greece, Iraq, Egypt, Syria, Morocco, Cyprus, Saudi Arabia, Libya, and Spain) is investigated. Two thermal transmittance values are applied to the building shell, a scenario with a very low one and a scenario with a higher one, to examine under which conditions the cooling performance is improved. A dynamic insulation configuration is also implemented, and its operation is studied for the cooling period of each city. It is concluded that in Southern European and Northern African regions building envelopes with lower thermal resistances perform better, while in even Southern regions an increased thermal resistance may prevent the heat from entering the building more effectively. With the switching insulation system, a great reduction in the cooling demands was reported, which reached up to 50% in Spain, and it was shown that in the southern regions the configuration’s operation should be customized to the ambient conditions to optimize its performance.

TEST OF A PILOT INSTALLATION OF A SOIL REGENERATOR FOR GREENHOUSES

The relevance of the development of ground regenerative heat exchangers is determined by the need to save energy resources for heating greenhouses at night and maintaining the required temperature level during the day. The aim of the work is to study working capacity of a ground regenerator for a greenhouse when testing a pilot plant in full-scale conditions. To achieve this goal the following main tasks were solved: experimental research of soil regenerator pilot plant operation was carried out, the heating period of nozzle and cooling period were determined by the obtained temperature curves, the coefficient of intercomponent heat exchange during the heating period was estimated, the rationality of material choice for granulated nozzle was proved, recommendations on improvement of soil regenerator design for industrial use were developed. The research was conducted on a pilot installation of a soil regenerator, which consists of a heat-exchange duct filled with granulated material and covered with a layer of insulation, and ducts with an exhaust duct fan installed at the outlet. Data on air and nozzle temperatures, which were taken during the day, were used to conduct thermal calculations and assess the efficiency of the ground regenerator. It was determined that the heating period at the selected loading mass of 15.5 kg is not long relative to the duration of the experiment and was 166 min. To increase the amount of accumulated heat it is recommended to increase the weight of the nozzle and air flow rate. It was determined that the coefficient of inter-component heat transfer during the heating period varied between 4 W/m2K and 9 W/m2K. In this case, the Bio number is in the range of 0.05 - 0.10, which allows us to conclude that the use of crushed stone as a nozzle material is rational. It is recommended to increase the thickness of insulation to 4.3 cm so that the heat loss from the heat exchange section does not exceed 5%, and to provide the installation of insulated plugs at the ends of the heat exchange section, closing after the end of the heating period.

Machining of Carbon Fibre Reinforced Polymer Composites: A Preliminary Investigation of High Power Fibre Laser

Carbon fibre reinforced polymer composites (CFRP) is one of the common materials used in machining by various manufacturing industries. The most persistent challenges during the machining, both concerning the consistency of machined surfaces and the properties of the material, are the difficulties such as fibre pull-out, delamination, and decomposition of the material matrix. This preliminary research highlights the laser machining of thick CFRP using a fibre laser of more than 1 kW. Laser machining experiments have been conducted to examine the ability of the fibre laser machine to cut thick CFRP through their high-quality laser beams. Based on the results, the study showed how the heat affected zone can be reduced when the higher cooling period is used. The effects of modulated beam mode include substantial reductions in HAZ compared with other experimental results. In all experimental attempts, substantial damage has occurred. The results are important in assessing the relationship between laser machining parameters and cutting results.

Estimation of coefficient of performance of thermoelectric cooler using a 30 W single-stage type

In this study, a single stage thermoelectric cooler (TER, of size: 21 × 14.2 × 13.5 cm) with thermoelectric module (TEM, of type inbc1-127. 05 with size 40 × 40 × 4.0 mm) and applied electrical power of 30 W and current of 2.5 A, was adopted to estimate the coefficient of performance (COP) of thermoelectric refrigerator (TER). The TER uses a fan to cool the heat exchange region of the TEM. The temperature of the fruit/vegetable samples used in this study was taken before and after cooling for a specific period. The temperatures at both the hot and cold sides of the TEM were also taken at every specific cooling period. The experimented TER can cool vegetable/fruit from about 27 to 5°C within 3 h. The aim of this study is to determine the COP of TER to ascertain the possible applications. The temperature gradient at the heat exchange section of TEM was used to estimate the average theoretical COP to be 0.99, the heat extracted from the cooling chamber and the power supplied was used to estimate the average practical cooling COP to be 0.52; which is within 0.4–0.7 standard COP for a single stage type of TER.

THERMAL PERFORMANCE OF FELT TYPE VEGETATED FACADE SYSTEMS IN A TEMPERATE CLIMATE DURING HEATING AND COOLING PERIODS

ABSTRACT Using vegetated facade systems (VFS) as a sustainable solution for existing and new buildings and evaluating thermal performance of these sytems are not a new concept. However, there is a gap in literature about measuring thermal performance of VFS applied on an insulated wall. Also, in the research literature, there are few studies measuring thermal performance of felt type VFS in temperate climates, and data about the thermal performance of VFS during winter periods is still scarce. Thus, the aim of the present study is to measure the thermal performance of a felt type VFS applied on a thermal insulated existing wall that us located in Kocaeli, Turkey, under Csa climate conditions during heating and cooling periods. Test results indicate that the felt type VFS acts as a shading device and has a positive contribution to the thermal performance of building walls during a cooling period. In daytime when there is a high amount of solar radiation, felt type VFS decreased exterior surface temperatures of the insulated existing wall by a maximum of 24.4°C, 32.2°C and 37.2°C, in spring, summer and fall periods, respectively. Additionally, indoor air temperatures of the vegetated facade were lower than indoor air temperatures of the reference facade with the maximum difference of 1.8°C during the cooling period. Also, test results indicate that the vegetated facade never dropped to below 0°C while exterior surface temperatures of the reference facade dropped below 0°C at nighttime in the winter period. Thus, it can be claimed that the felt type VFS behaves as a thermal buffer and enhances the thermal performance of the exterior wall of the existing building during heating periods at nighttime. As a conclusion, although differences between exterior surface temperatures of vegetated and reference walls were high, differences between interior surface temperatures of vegetated and reference walls were not meaningful. That is due to the fact that the existing building exterior wall assembly includes 5 cm thickness thermal insulation material which enhance the thermal performance of the brick wall. Finally, according to solar reflectance results, it can be claimed that vegetated facade systems have a positive effect on reducing urban heat island effect.

Diagnostic Protocol for Thermal Performance of District Heating Pipes in Operation. Part 2: Estimation of Present Thermal Conductivity in Aged Pipe Insulation

Buried and operating district heating (DH) pipes are exposed to thermal degradation of their polyurethane (PUR) insulation over time, and their status is hard to assess without excavation. By using DH pipe valves in manholes as measurement points during a shutdown with an ensuing cooling period, non-destructive assessments can be performed. This study compares new improved field measurements with numerical simulations of the temperature decline in drainage valves and shutdown valves. The drainage valve measurements were used to thermally assess part of a buried DH network. Results indicate that by using the drainage valves as measurement points in a cooling method, the thermal conductivity of the buried DH network could be predicted with an accuracy of >95%. In addition, a general diagnostic protocol has been established for assessing the thermal status of a DH network, ready for network owners to use.

Vulnerability of Drop Ceilings in Roadway Tunnels to Fire-Induced Damage

Roadway tunnels often include a reinforced concrete drop ceiling that is hung from the liner to create a plenum that facilitates ventilation and houses utilities. Drop ceiling panels are lightweight compared with the much thicker tunnel liner and can experience significant damage from a fire on the roadway below. This paper examines the flexural response of drop ceiling panels in two representative tunnels to standard fire curves as well as several realistic fires due to vehicular accidents. Standard fire demands as per the Rijkswaterstaat and ASTM E1529 fire curves are uniformly applied to the ceiling panels, and heat exposure contours for typical vehicle fires with heat release rates of 30, 100, and 200 MW are generated from the software CFAST. The finite element analysis software SAFIR is used to evaluate the thermo-mechanical behavior of the ceiling panels when subjected to various thermal demands from the fire below. The analysis results indicate that drop ceiling panels are highly vulnerable to fire-induced damage and potential collapse both during a fire’s active heating phase (from simultaneous loss of capacity and restraint of thermal expansion) and during the subsequent cooling period (from tension that develops when the permanently deformed panel thermally retracts). The potential for fire-induced damage or collapse of the drop ceiling panels can be mitigated by reducing the fire hazard, removing the drop ceiling, or enhancing the fire resistance of the panels via the application of passive protection or structural hardening.

Transient thermal analyses of an integrated brake rotor and wheel hub for heavy duty vehicles

In this study, transient thermal analyses for a new integrated rotor and wheel hub concept are performed by consideration of convection, conduction and radiation effects. Test methods used for the characterization and certification purposes are constructed in a simulation environment and the effect of different ventilation vanes and rotor-hub arrangements on heat transfer mechanism is examined and the details are summarized for a reliable simulation process. Validated procedures are used to report a series of characterization and certification analyses, namely; CFD analyses including wheel assembly, cooldown analyses, R13 repeated stop fade and alpine hot descent analyses for current design and new integrated rotor and hub pair for alternative ventilation vane designs. The analyses are especially focused on predicting the cooling period and predicting maximum bearing temperatures for normal and excessive loading scenarios. To provide benchmark a commercial integrated rotor and hub pair used in heavy duty vehicles is also analysed. The average convective heat transfer coefficient and cooldown period of proposed integrated brake rotor are improved by 117.3% and 30.5% compared to the base design. The maximum wheel bearing temperature is decreased by 27.0% and by 27.1% for the proposed integrated brake rotor and wheel hub compared to the benchmark model, in accordance with the repeated stop and alpine hot descent analyses. In addition, the total weight reduction of 10 kg (15%) according to the base design is achieved.