Study on Low Temperature Drying Characteristics of Chicken Manure in a Humid Environment

Abstract

Drying chicken manure with exhaust air from a chicken house is a new manure management method developed in recent years. The majority of the heat for this drying method comes from the waste heat of ventilation in a poultry house or ambient air, so the drying process is carried out at a low temperature. When met with continuous rain or when the wet curtain in the chicken house is turned on, the relative humidity of the exhaust air from the chicken house will rise to high levels, and the drying process will be under the condition of high relative humidity. In order to explore the low-temperature drying characteristics of chicken manure in a humid environment, drying experiments were carried out in an experimental cross-flow drying system. The experiment mainly studied the effect of process parameters such as drying temperature, air velocity, and manure layer thickness on the low-temperature drying characteristics of chicken manure in a humid environment. The results showed that the low-temperature drying process of chicken manure in a humid environment only had a falling rate period, with no accelerated or constant rate period. Additionally, five common thin-layer drying models (Lewis model, Page model, Henderson and Pabis model, Wang and Singh model, and Exponential model) were applied to simulate the performance of the manure drying process. The exponential model was considered to be more suitable for describing the low temperature drying process in a humid environment, and the effective diffusivity changed between 6.37 × 10−7 and 2.17 × 10−6 m2/h.