Non-technological barriers to the diffusion of energy-efficient HVAC&R solutions in the food retail sector

SuperSmart is an European Union (EU) project aiming at speeding up the uptake of energy-efficient re- frigeration, heating and cooling solutions for Europe\u2019s food retail sector, reducing its energy use, lowering its environmental footprint and increasing its economic benefits. The project pursues the removal of non- technological barriers to efficient heating & cooling in the European food retail sector and supports the introduction of a new EU Ecolabel for food retail stores. Non-technological barriers have been mapped and categorized by preliminary interviewing food re- tail sector stakeholders. While highlighting a general positive attitude towards energy efficiency of the sector stakeholders, the results of the survey reveal the need for specific actions focused on improving the knowledge level of technical staff, from the planning and design stage down to servicing and main- tenance. Raising awareness about available technology and financial support is also required. In general terms, barriers are always perceived as stronger when moving North to South, and West to East in Europe, thus emphasizing the need for homogenization of virtuous practices and attitudes throughout Europ

Thermophysical, microstructural characterization and non-destructive control of TBCs by photothermal and thermographic techniques: some lessons learned

Since several years, photothermal and thermographic techniques have been used to perform the thermo-physical characterisation of TBCs and the non-destructive assessment of TBC integrity. Furthermore, in the last decade some attempts to use these techniques for carrying out a non-destructive microstructural characterization have been done, as well. In this talk the description of a thermographic technique able to simultaneously measure the through-the-thickness and the in-plane thermal diffusivity of free standing TBCs samples and thus giving evidence of the typical microstructural anisotropy of APS TBCs will be provided [1]. Furthermore, some effects of the laser radiation used in a laser flash experiment on the TBC thermal diffusivity and a new model for fitting the experimental data will be presented [2,3]. The main results of an activity focused to identify potentialities and limitations of using Laser flash experiments on multilayered samples for estimating thermal diffusivity of TBCs samples will be provided. A theoretical and experimental analysis of the real capabilities of infrared techniques to estimate the porosity content and the microstructure of porous ceramic materials such as thermal barrier coatings (TBCs) by studying thermal diffusivity variations when pores are filled with air or vacuum will be provided [4,5]. Please click Additional Files below to see the full abstract

A novel R744 multi-temperature cycle for refrigerated transport applications with low-temperature ejector: Experimental ejector characterization and thermodynamic cycle assessment

A novel vapor-compression system concept employing carbon dioxide as the refrigerant is proposed to serve the needs of a typical medium-size refrigerated truck used for multi-temperature (MT and LT) goods delivery. The system design is based on the implementation of an ejector as the only component increasing the refrigerant pressure from the LT evaporation pressure to the MT evaporation pressure, thus providing cooling effect at two different temperature levels with only one stage of compression. The ejector was experimentally tested and its ability to effectively entrain mass flow rate from low pressure suction conditions (corresponding to a LT evaporation temperature of −25 °C) was assessed. Lower external ambient temperatures and consequent lower expansion energy available at the ejector motive nozzle leads to a reduction of the maximum achievable pressure lift. Moreover, a significant degradation of the ejector performance towards the highest pressure lifts is experienced. Based on the ejector experimental data, a numerical evaluation of the proposed cooling unit performance has been performed, highlighting that in design conditions (LT evaporation at −25 °C) the cooling unit provides a LT freezing power ranging between 1.1 kW and 2.3 kW and a corresponding minimum MT cooling power ranging between 5.1 kW and 3.8 kW, depending on the chosen ejector lift. The MT cooling power can be further increased by increasing the compressor mass flow rate. The system COP is maximized at the maximum available lift provided by the ejector. © 2023 The AuthorsA novel R744 multi-temperature cycle for refrigerated transport applications with low-temperature ejector: Experimental ejector characterization and thermodynamic cycle assessmentpublishedVersio

Experimental evaluation of the performance of an ejector for a single compression multi-temperature CO2 refrigeration unit

A novel vapor-compression system concept employing carbon dioxide as the refrigerant is proposed to serve the needs of a typical medium-size refrigerated truck used for multi-temperature (MT and LT) goods delivery. The system design is based on the implementation of an ejector as the only component increasing the refrigerant pressure from the LT evaporation pressure to the MT evaporation pressure, thus allowing the realization of a unit providing cooling effect at two different temperature levels with only one stage of compression. The ejector was experimentally tested in order to evaluate its ability to effectively entrain mass flow rate from very low pressure conditions at the suction nozzle, corresponding to the LT evaporator outlet conditions. In addition, a simple preliminary thermodynamic evaluation of tExperimental evaluation of the performance of an ejector for a single compression multi-temperature CO2 refrigeration unitacceptedVersio

Innovative layout for electric powered refrigeration for insulated trucks: the integration of photovoltaic generator

Small insulated truck refrigeration units are usually powered by the internal combustion engine used for the vehicle traction, as the system size does not require the use of a dedicated prime engine. The paper presents an innovative layout where an electrically driven compressor is connected to a battery pack, which is powered by a photovoltaic generator placed on the roof of the insulated box. The battery packs are also connected to the vehicle alternator, which is used as a backup source. A fully functional prototype of the system is presented and characterized. Numerical simulations are then used to forecast the impact of the solar contribution to the system performances under different ambient conditions. Numerical simulation results demonstrate the proposed system can sustain itself for most of the considered cases, resulting in a significant reduction of the annual consumption for the vehicle

CFD modelling of an operating theater

The operating theater is the environment inside the hospital that requires the greatest deal of attention in the choice of the devices for air supply, diffusion and recovery. The design of Heating, Ventilation and Air Conditioning (HVAC) systems dedicated to these environment plays a crucial role to drastically reduce the risk of infection for patients, in addition to the maintenance of adequate thermo-hygrometric comfort conditions for the medical team. As a result, a lower risk of sepsis has been reported thanks to a cleaner air injection in operating theaters. In this work, the authors have reproduced numerically the air distribution inside an operating theater, where a swirl diffuser system is present. The numerical results have been validated against the experimental data obtained during field campaign. The objective of the present work is to develop an effective and robust numerical model able to reproduce the fluid dynamics phenomena inside operating theaters