Experimental study of a falling film distiller for an ammonia-water absorption refrigeration cycle in a horizontal tube bundle

Author(s)

Elí Wilfredo Zavaleta Aguilar

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Eletrotécnica e Energia (IEE/BT)
• Defense date: 2015-03-04

Examining board members

Jose Roberto Simões Moreira; Patricia Helena Lara dos Santos Matai; Marcos de Mattos Pimenta; Gherhardt Ribatski; Marcelo da Silva Rocha

• Advisor: Jose Roberto Simões Moreira

Abstract

This work presents the experimental study of an important component of an ammonia-water absorption refrigeration cycle - the distiller. The distiller is responsible for producing high purity ammonia vapor from a concentrated ammonia-water liquid solution. It is analyzed here a falling film distiller composed solely of two elements: the generator and the rectifier. The generator consists of a horizontal tube bundle which internally hot thermal synthetic oil passes through. The ammonia-water concentrated solution flows externally on the tubes making a falling film resulting in a wet ammonia vapor. The rectifier, which is also a horizontal tube bundle, cools down the wet ammonia vapor and condenses part of water content, thus producing high purity distilled ammonia vapor. The aim of this work is to analyze the influence of different parameters on the operation of the distiller, respecting the concentration and the mass flow rate of distillate ammonia produced. For that, an experimental setup that allows to vary the temperature, the mass flow rate and the concentration of the ammonia-water solution, as well as, the thermal oil temperature in the generator and the cooling water temperature in the rectifier was built. This experimental setup can work at internal pressures up to 20 bar and temperature up to 150 °C. The results showed that the distilled ammonia concentration enhances when increased the concentrated solution mass flow rate, and when the temperature of the rectifier, generator and the concentrated solution decreased. However, except in the reduction of the rectifier temperature, whenever the purity of distilled ammonia increased, its mass flow rate decreased. There were performed tests with two concentrations of the concentrated solution: 37 and 49 %. The ammonia distilled purity increases for the higher concentration, reaching up to 99.74 %. There were also analyzed the liquid distribution system on the pipes, the intertube flow mode, furthermore, the average Nusselt number for the ammonia-water falling film mixture. (AU)

• FAPESP's process: 10/16304-0 - Experimental study of a falling film distillation column for an ammonia/water absorption refrigeration cycle
• Grantee: Eli Wilfredo Zavaleta Aguilar
• Support Opportunities: Scholarships in Brazil - Doctorate