Energy Efficiency of Combined Ovens

The management optimization of energy fluxes applied in the professional cooking sector has an attractive potential, and represents a big step ahead, because it is characterized by a high energy demand and has a large diffusion all over the world. Furthermore, professional cooking sector still presents significant possibilities for energy efficiency enhancements, in both design solutions and operating strategies. The present study focuses on energy efficiency analyses on combined ovens for professional use. In the initial phase of the evaluation, energy efficiency standards EFCEM, ENAC and ASTM have been compared with experimental results. Discrepancies were shown by means of a systemic application of the mentioned standards to a specially instrumented prototype of professional oven. Different test conditions do not allow a meaningful comparison of test results, leading to the definition of a new methodology for the energy efficiency evaluation of a combined oven. structured on the experimental analysis of the balance of fluxes incoming and outcoming from the oven in different cooking modalities. It allows improving the knowledge of the machine and, afterwards, helps in the definition of different design choices, derived from the analysis

A control system for preventing cavitation of centrifugal pumps

Cavitation is a well-known phenomenon that may occur, among other turbo-machines, in centrifugal pumps and can result in severe damage of both the pump and the whole hydraulic system. There are situations in which, in principle, the cavitation could be avoided by detecting the condition of incipient cavitation, and changing slightly the working point of the whole system in order to move away from that condition. In the present paper two simple closed-loop control strategies are implemented, acting on the pump's rotational speed and fed by the measurements of a set of inertial sensors. In particular, the research is focused on a centrifugal pump normally employed in hydraulic systems. The pump operates in a dedicated test rig, where cavitation can be induced by acting on a reservoir's pressure. Three accelerometers are installed in the pump body along three orthogonal axes. An extensive set of experiments has been carried out at different flow rates and a number of signals' features both in the time domain and in the frequency domain have been considered as indicators of incipient cavitation. The amount of energy of the signal captured by the accelerometer in the component orthogonal to the flow direction, in the band from 10 to 12.8 kHz, demonstrated to be effective in detecting the incipient cavitation, by selecting a proper (condition-dependent) threshold. Therefore, two simple controllers have been designed: the first regulates the speed of the pump, to recover from cavitation, bringing the indicator back to the nominal value, while the second allows to reduce the pump's rotational speed when the cavitation detector indicates the incipient cavitation and restoring the nominal speed when possible. The latter approach is rather general, because the threshold-based detector can be substituted by any detector providing binary output. Experimental results are reported that demonstrate the effectiveness of the approach

Energy Efficiency Improvement in Professional Ovens

Tackling the climate change by reducing energy consumption is among the biggest, most urgent challenges society is facing and requires a continuous efficiency improvement of thermal systems.With the aim of reducing energy consumption and improving energy efficiency of professional appliances, this thesis is the results of the investment Electrolux Professional Spa has made. The industrial research started with an analysis of the state of the art of the energy standards applied to a professional oven. It continues, identifying a new methodology for the energy efficiency evaluation of a combined oven structured on the experimental analysis of the balance of fluxes in coming and out coming from the oven in different cooking modalities. The new developed methodology is based on the first principle of thermodynamics and it helped in the identification and application of a series of technical options for improving the energy efficiency of an oven. From the analysis is emerged that the thermal insulation and the washing system were among the main potential energy savings improvements in the overall efficiency. Based on the constitutive energy conservation equations of a professional oven, a dynamic model has been developed. It was build up in order to get a general understanding of the best possible configurations and combinations of insulation materials for the cavity walls. The code was developed in Matlab\ua9 and it was validated by comparison with a set of experimental data obtained with a current production model. After the model development, the washing plant of a professional appliance was optimized in terms of energy efficiency, water consumption, detergent and rinsing agent consumption. During the experimental test on a prototype of the washing circuit, a possible cavitation problem has appeared. Generally, in the hydraulic circuit of a professional appliances, in particular in a oven, the working fluid is a solution of water and detergent at 70 \ub0C. The actual trend in this kind of professional appliances is to reduce both energy consumption and time needed for cleaning process: this involves short washing cycles conducted at low temperatures with a solution of water and highly concentrated chemistry. High concentrated chemistry could impact on the working conditions of the pump and on cavitation. The wide range of variables affecting cavitation has led to the development of a laboratory rig for testing different sizes of centrifugal pumps with aqueous solutions representative of those used in the warewashing sector. This test rig permits measuring pump performances at various operating conditions, in order to obtain its characteristic curves, and also forcing cavitation to measure its Net Positive Suction Head required (NPSHr) at different flow rates. The pump test rig allows also testing various configurations of the pump at different cavitation conditions, obtained by changing not only the suction pressure and temperature of the fluid but also its properties, adding detergents and additives. Cavitation inception can be detected measuring both the corresponding prevalence decrease and the change of vibration and noise level. A representative chemical component present in detergents (Polyox WSR 301) has been selected and tested at different concentrations in the rheometer in order to identify the concentration values at which the solution switch from the diluted to the concentrated regime. It has been also measured the influence of the chemical components on the pump characteristic curves and the vibration level. The results are quite impressive, because with the increasing of the concentration there is a decreasing of the pump vibrations and also the characteristic curves at certain conditions are improved. In literature there are no studies analyzing the impact of detergent components on pump vibration induced by cavitation

PROCESS CHAIN SIMULATION : VIRTUAL REALITY TO MACHINE-VR2M

The networking of production processes by means of information technologies (IT) has become a major field of development within industry and research. The main target is to interlink autonomous production systems to an intelligent production line, where products itself organise and control their manufacturing. This new attempt in production is -actual in Germany described under the definition "Industry 4.0", the fourth industrial revolution. Basically, the essential hardware and software to meet this objectives has been developed in other branches and is able to upgrade machines and handling systems to cyber-physical systems. The crucial issue to design an autonomous, intelligent production line is to generate the exact process data for each production step, to verify this data and to transfer it into the individual machine control. The characteristics of this main problem increases with the degree of interactions between the processes in the production line. In the woodworking industry, the process chain of profiling has a high degree of interactions. The individual production steps are strictly based on another and the result of a process effects the subsequent one respectively. To network these processes and add IT, an integrated IT system with individual CAD/CAM system for each process type is needed. The estimation of the interactions is done by the simulation of the whole process chain in a virtual reality before the real production. This enables to verify the process data, and to benefit from simultaneous engineering. Besides the essential algorithms to calculate the process data for the different process types and estimate the geometry corruptions due to systematic errors and manufacturing tolerances, the consideration of the material behaviour during the production is the determining factor to get valid data for the process chain. The shrinking and swelling of wood and woodbased materials due to a change of moisture content causes a geometry corruption and requires algorithms to simulate this behaviour in the virtual real ity. The result of these algorithms for the processes and the material behaviour are the exact process data for a specific profile. The database for the calculations and the data storage is a developed product data model. This product data model forms the gateway for the simulation in the virtual reality to the machine controls

PROCESS CHAIN SIMULATION : VIRTUAL REALITY TO MACHINE-VR2M

The networking of production processes by means of information technologies (IT) has become a major field of development within industry and research. The main target is to interlink autonomous production systems to an intelligent production line, where products itself organise and control their manufacturing. This new attempt in production is -actual in Germany described under the definition "Industry 4.0", the fourth industrial revolution. Basically, the essential hardware and software to meet this objectives has been developed in other branches and is able to upgrade machines and handling systems to cyber-physical systems. The crucial issue to design an autonomous, intelligent production line is to generate the exact process data for each production step, to verify this data and to transfer it into the individual machine control. The characteristics of this main problem increases with the degree of interactions between the processes in the production line. In the woodworking industry, the process chain of profiling has a high degree of interactions. The individual production steps are strictly based on another and the result of a process effects the subsequent one respectively. To network these processes and add IT, an integrated IT system with individual CAD/CAM system for each process type is needed. The estimation of the interactions is done by the simulation of the whole process chain in a virtual reality before the real production. This enables to verify the process data, and to benefit from simultaneous engineering. Besides the essential algorithms to calculate the process data for the different process types and estimate the geometry corruptions due to systematic errors and manufacturing tolerances, the consideration of the material behaviour during the production is the determining factor to get valid data for the process chain. The shrinking and swelling of wood and woodbased materials due to a change of moisture content causes a geometry corruption and requires algorithms to simulate this behaviour in the virtual real ity. The result of these algorithms for the processes and the material behaviour are the exact process data for a specific profile. The database for the calculations and the data storage is a developed product data model. This product data model forms the gateway for the simulation in the virtual reality to the machine controls