Thailand is the agricultural country. Many types of agricultural products cannot keep for over season
and moreover, low price problem. For solving problem, agricultural products were transformed and keep
for using in over season. Because of drying is simple method and can keep product for a long time.
Therefore, drying process is used for solving low price problem. Drying is dehumidification process of
product by using heat transfer to product for dehumidification. Normal energy for drying system is
electrical energy, oil and fuel gas. These energy are waste energy and high cost. Heat pipe is a simple
heat exchanger for heat transfer from difference temperature of two sources. Heat pipe is many types.
Oscillating heat pipe (OHP) is one type of heat pipe [1]. Normally, OHP made from capillary tube and had 3 types of closed end oscillating heat pipe (CEOHP), closed-loop oscillating heat pipe (CLOHP) and
closed-loop oscillating heat pipe with check valves (CLOHP/CV) and OHP has three sections of
evaporator, adiabatic and condenser sections [3]. CLOHP/CV is the best of all [4]. In 2007, CLOHP/CV
was applied using for hot air drying process. It was found that, CLOHP/CV air-preheater can reduce
relative humidity and increase temperature of air before into drying system [2]. Nevertheless, CLOHP/CV
air-preheater by P. Meena had problem in hot air distribution.