Abstract
During the beginning of the XX century lyophilization was developed as an alternative technology to extend the storage time for fruit and vegetables or other kind of food; however, the energetic consumption of this technology makes it not an option for common food producers, less over for those one that work by the open field cultivation technique. The main energy consumption in a lyophilization systems are the motors from the vacuum pump and from the refrigerant compressors; due to the temperature range needs the lyophilization systems use to have more than one cooling thermodynamic system based on vapor compression. This paper describes an experimental methodology to get a complete state transfer functions matrix, based on the graphical analysis of the concerned transfer functions magnitude spectra. This experimental data came from a set of test performed at the National Laboratory for Cooling Technology Research (LaNITeF) at the Engineering Center for Industrial Development (CIDESI). The intention of this transfer functions matrix is to be applied in a control strategy to then optimize the energetic performance of the concerned lyophilization system. This function transfer matrix is considered complete because there is not a dynamic order reduction considering its degrees of freedom. The transfer functions matrix describes the dynamic relationship between both the inputs variables that describe the energetic consumption of the lyophilization system, and the ambient conditions, as well as the output variables that represent the dynamical states vector with the variables of interest from the concerned process. The simulation from an experimental scenario worked as the graphical validation of the transfer functions matrix characterized experimentally, so the main conclusion of this scientific work is that this transfer functions matrix can be used as dynamic model to implement control and optimization algorithms.
Highlights
IntroductionBecause of the cooling speed and load capacity, traditional refrigeration and freezing process based on the vapor compression technologies are the most used alternatives for the perishables products conservation (production, storage, transportation, distribution and exhibition) [3 – 5]
Because of the cooling speed and load capacity, traditional refrigeration and freezing process based on the vapor compression technologies are the most used alternatives for the perishables products conservation [3 – 5].It is estimated that just in Mexico the 30 % of the food production is wasted because of several issues with the cold chain and refrigeration [1]; and it occurs almost the same with the final availability for the perishable medicine in rest of Latin America [2].But the wastes from the production of food and medicine is not the only opportunity for the refrigeration process; because, nowadays the temporal cultivation of fruits and vegetable through open field techniques, does not represent a convent opportunities for communities that have this economical access naturally
It is well known that the natural cooling process into the vapor compression technologies affects the electrochemical properties of food and medicine [6, 7]; so, that, since the beginning of the XX century the lyophilization process appears [8] by being an alternative for the food and medicine preservation process, because its preserves their structural composition by a fast cooling process into a vacuum ambient for the water extraction [9]
Summary
Because of the cooling speed and load capacity, traditional refrigeration and freezing process based on the vapor compression technologies are the most used alternatives for the perishables products conservation (production, storage, transportation, distribution and exhibition) [3 – 5]. It is well known that the natural cooling process into the vapor compression technologies affects the electrochemical properties of food and medicine [6, 7]; so, that, since the beginning of the XX century the lyophilization process appears [8] by being an alternative for the food and medicine preservation process, because its preserves their structural composition by a fast cooling process into a vacuum ambient for the water extraction [9] Both lyophilization sub-stages mainly defined as the fast cooling and the vacuum ambient are high energy expending process; due to the motors power that move the refrigerant compressors and the vacuum pumps. This results analysis works as reference for the conclusions synthesis in the last chapter
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