Implementing robust thermodynamic model for reliable bubble/dew problem solution in cryogenic distillation of air separation units

High accuracy in Equations of State (EoSs) is becoming a more and more critical aspect for design and operational purposes in different areas of chemical and process engineering. It is well-known that improper predictions of mixture properties provide large deviations in process simulations, process control actions, estimation of operative conditions, assessment of performance indexes and optimal unit/process design. These deviations are strongly emphasized when typical operating conditions appear rather severe. One of the most challenging application sectors is represented by cryogenic separations and especially in case their nominal operating conditions approach the critical point. Air Separation Units (ASUs) are the ideal application field to demonstrate these criticisms. In addition, dedicated EoSs sometimes lacks in implementation details and thermodynamic parameters, making the reliability target impossible to be achieved. The present paper is aimed at bridging the current gaps in the implementation of Bender EoS for the reliable prediction of air mixture properties as well as the reliable simulation of ASU plants. The implementation requires the description of robust and efficient algorithms. At last, a quantitative comparison between the proposed approach and the existing solutions is provided

Thermal characterization of insulating materials

The strict energy saving standards are based on the declared values of the materials, i.e. U-value, thermal conductivity or thermal capacity. To this end, proper knowledge of the thermophysical properties of the wall components is needed, especially with regard to new lightweight technologies that are being used in building construction/refurbishment, under the dynamic conditions of the Mediterranean climate, where one of most important parameters of building materials is their heat capacity because of the influence of solar radiation energy. With this regard, the actual heat capacity value, obtained in laboratory tests, is typically quite different from the nominal one. So, this paper reviews several methods of calculating the heat capacities of materials and several worldwide applications, with the aim of providing an overview of the thermal behaviour of lightweight insulation materials and their implications for energy and indoor comfort. Finally, the authors propose a simple method able to evaluate the specific heat capacity of real scale building materials with a ~5% of uncertaint

Uncertainty in the evaluation of the Predicted Mean Vote index using Monte Carlo analysis

Today, evaluation of thermohygrometric indoor conditions is one of the most useful tools for building design and re-design and can be used to determine energy consumption in conditioned buildings. Since the beginning of the Predicted Mean Vote index (PMV), researchers have thoroughly investigated its issues in order to reach more accurate results; however, several shortcomings have yet to be solved. Among them is the uncertainty of environmental and subjective parameters linked to the standard PMV approach of ISO 7730 that classifies the thermal environment. To this end, this paper discusses the known thermal comfort models and the measurement approaches, paying particular attention to measurement uncertainties and their influence on PMV determination. Monte Carlo analysis has been applied on a data series in a “black-box” environment, and each involved parameter has been analysed in the PMV range from −0.9 to 0.9 under different Relative Humidity conditions. Furthermore, a sensitivity analysis has been performed in order to define the role of each variable. The results showed that an uncertainty propagation method could improve PMV model application, especially where it should be very accurate (−0.2 < PMV<0.2 range; winter season with Relative Humidity of 30%)

Thermal Parameters Measurements of High-Rise Building Envelope

In buildings, to ensure the thermal comfort of the occupants and to keep the energy consumption as low as possible, a correct design of the thermal system is necessary. To do so, an appropriate determination of the thermo-physical properties of the wall materials is needed, particularly; new light-weight building technologies are widely used in the construction of the building envelope. One of these parameters, particularly important in Mediterranean climatic dynamic conditions is the heat capacity, due to the presence of the sun’s energy contribution in hot and cold seasons. The value of the heat capacity in such like materials is typically quite different from the declared parameter, obtained in laboratory tests. To solve this problem, the authors propose a simple method for the evaluation of the specific heat capacity of the thermal properties of real scale building materials

LAPAROSCOPIC REPAIR OF AN INCISIONAL HERNIA L2 ZONE - W2 (EUROPEAN HERNIA SOCIETY CLASSIFICATION) INTRAPERITONEAL ONLAY MESH REINFORCEMENT (IPOM-PLUS) IN EMERGENCY

The laparoscopic repair of incarcerated incisional hernias is still debated in the literature. The recent EAES/EHS guidelines state that laparoscopic surgery is not contraindicated and may be considered in selected patients with incarcerated hernia. This video shows the case of an 83-year-old woman with an incarcerated incisional hernia in the left iliac fossa (L2 zone – W2) successfully managed laparoscopically with an intraperitoneal onlay mesh reinforcement (IPOM-plus)