| The cycles system of heat pump drying with intermediate heat-exchanger and two-level compression was developed as well as the theoretical analysis of thermodynamics and comparison were conducted. The less energy consumption of heat pump with two-level compression was proved.The theoretical calculation method of bypass ratio was induced and the theory of dew point temperature depression was raised firstly.The mathematical models for heat pump drying system, air-conditions in the lumber drying kiln and bypass ratio were formed firstly. The relationships between parameters of heat pump system, kiln conditions and bypass of air were analyzed. Based on requirements of lumber drying process, design methods for high-temperature heat pump with two-level even multi-level compression were developed firstly.Experiment stage for high-temperature heat pump drying of lumber was established and the variation patterns of different kinds of parameters for lumber drying with single-level, single-two-level and two-level compression as well as the effects of air bypass were investigated by drying experiments of Masson's pine lumber. The theoretical analysis for heat pump drying was verified. Total energy consumption of single-level compression is higher than that of two-level compression by 23.05%. Energy recycling rate of lumber drying process with single-level compression is 25.55% and that two-level compression is 33.63%. Energy recycling rate is in direct proportion with dewatering capacity, that is, the larger the dewatering capacity is, the higher the energy recycling rate is.
|
PDF Full Text Request