Diseño y construcción de un prototipo de sistema de bomba de calor para una secadora de cacao rotativa de flujo constante.

Abstract

This work arises from developing a new artificial drying method to those already known, such as solar drying and artificial drying using diesel fuel or gas. These are indicated as being the most used in Machala, and also to help with a goal in the INIAP strategic plan which establishes that by the year 2018 -2022 in the agribusiness, at least one technological idea for drying cocoa must be developed. For the design of the prototype of a heat pump drying system, a numerical model was first established where the partial differential equations based on Fick's second law and the Fourier heat conduction equation by finite elements were solved using Matlab, to these resolutions humid air properties and mass balance were added in a dryer. To predict the behavior of the temperature and humidity of the drying air inside the chamber and of the variation of the humidity of the cocoa beans as a function of time. From the numerical model, it was possible to link with the thermodynamic equations of the heat pump and the concepts of pressure losses in the ducts for their design and to be able to establish the flows and temperatures in each section of the system. From the construction of the prototype, tests were carried out to validate the numerical model of the humidity variation of the cocoa beans as a function of time and a mean relative error of 10.88% was obtained with respect to the experimental one. In addition, the mean relative error of the temperature and humidity at the exit of the drying chamber was obtained at 4.32 and 10.5% respectively. Regarding the drying time, a humidity of 8% in the cocoa beans was obtained in 21 hours, when comparing with the solar drying a 30% reduction of the time was obtained.