文档介绍：International Journal of Heat and Mass Transfer 49 (2006) 1946–1957
ate/ijhmt
Free convection frost growth in a narrow vertical channel
G. Tanda *, M. Fossa
Dipartimento di Ingegneria della Produzione, Termoenergetica e Modelli Matematici (DIPTEM), Universita` degli Studi di Genova,
via all’Opera Pia 15a, I-16145 Genova, Italy
Received 8 November 2004
Available online 10 January 2006
Abstract
Processes involving heat transfer from a humid air stream to a cold plate, with simultaneous deposition of frost, are of great impor-
tance in a variety of refrigeration equipment. In this work, frost growth on a vertical plate in free convection has been experimentally
investigated. The cold plate ( m high, m wide) was placed in a narrow ( m high, m deep) vertical channel open at the
top and bottom in order to permit the natural circulation of ambient air. The cold plate temperature and the air relative humidity were
varied in the À40 to À4 °C and 31–85% range, respectively, with the air temperature held fixed at 27 °C (±1 °C). The main quantities
(thickness, temperature and mass of frost, heat flux at the cold plate), measured during the time evolution of the process, are presented as
functions of the input parameters (relative humidity and cold plate temperature); in particular, the role exerted by the plate confinement
on the frost growth is discussed. Data are recast in order to pact parameters able to correlate with good accuracy frost thick-
ness, mass and density data.
Ó 2005 Elsevier Ltd. All rights reserved.
Keywords: Frost; Vertical channel; Free convection; Heat/mass transfer
1. Introduction other crystals resulting in a uniform frost layer, (c) a frost
layer full growth period, when the frost surface reaches 0 °C
Frost formation occurs when humid air passes over a and a cyclical process of melting, freezing and deposition
surface whose temperature is below the water freezing occurs until frost formation stops. The