TY - JOUR

T1 - Factors affecting process temperature and biogas production in small-scale rural biogas digesters in winter in northern Vietnam

AU - Cuong, Pham Hung

AU - Vu, C.C.

AU - Sommer, Sven G.

AU - Bruun, Sander

PY - 2014

Y1 - 2014

N2 - This study investigated the main factors influencing digester temperature and methods to reduce heat losses during the cold season in the subtropics. Four composite digesters (two insulated and two uninsulated) were buried underground to measure their internal temperature (°C) at a depth of 140 cm and 180 cm, biogas production and methane (CH4) concentration in biogas from August to February. In parallel the temperature of the air (100 cm above ground), in the slurry mixing tank and in the soil (10, 100, 140, and 180 cm depth) was measured by thermocouple. The influent amount was measured daily and the influent chemical composition was measured monthly during the whole experimental period. Seasonal variations in air temperature significantly affected the temperature in the soil, mixing tank and digester. Consequently, biogas production, which is temperature dependent, was influenced by the season. The main factors determining the internal temperature in the digesters were insulation with Styrofoam, air temperature and temperature of slurry in the mixing tank. Biogas production is low due to the cold climate conditions in winter in Northern Vietnam, but the study proved that storing slurry in the mixing tank until its temperature peak at around 14:00 h will increase the temperature in the digester and thus increase potential biogas production. Algorithms are provided linking digester temperature to the temperature of slurry in the mixing tank.

AB - This study investigated the main factors influencing digester temperature and methods to reduce heat losses during the cold season in the subtropics. Four composite digesters (two insulated and two uninsulated) were buried underground to measure their internal temperature (°C) at a depth of 140 cm and 180 cm, biogas production and methane (CH4) concentration in biogas from August to February. In parallel the temperature of the air (100 cm above ground), in the slurry mixing tank and in the soil (10, 100, 140, and 180 cm depth) was measured by thermocouple. The influent amount was measured daily and the influent chemical composition was measured monthly during the whole experimental period. Seasonal variations in air temperature significantly affected the temperature in the soil, mixing tank and digester. Consequently, biogas production, which is temperature dependent, was influenced by the season. The main factors determining the internal temperature in the digesters were insulation with Styrofoam, air temperature and temperature of slurry in the mixing tank. Biogas production is low due to the cold climate conditions in winter in Northern Vietnam, but the study proved that storing slurry in the mixing tank until its temperature peak at around 14:00 h will increase the temperature in the digester and thus increase potential biogas production. Algorithms are provided linking digester temperature to the temperature of slurry in the mixing tank.

KW - Air and Soil Temperature

KW - Digester Temperature

KW - Insulation

KW - Season

KW - Simple Biogas Digester

U2 - 10.5713/ajas.2013.13534

DO - 10.5713/ajas.2013.13534

M3 - Journal article

C2 - 25050049

AN - SCOPUS:84903310807

VL - 27

SP - 1050

EP - 1056

JO - Asian-Australasian Journal of Animal Sciences

JF - Asian-Australasian Journal of Animal Sciences

SN - 1011-2367

IS - 7

ER -