Lime (Citrus aurantifolia) is an important agricultural product in Thailand. Lime has been used to prevent scurvy, a disease caused by a deficiency of vitamin C. Traditionally, lime has been used as a remedy for indigestion, heartburn and nausea. It also has cooling effects on fevers and can help ease coughs and various respiratory disorders (3), (7). The preservation or modification techniques of lime during seasoning are necessary in order to preserve lime for off season, apply for other purposes and also to control the price of lime. In this study, the vacuum dryer technique is designed to produce lime juice powder in order to preserve lime products. Vacuum drying is one of the best methods for food drying equipment and producing final products of highest quality as comparing to other drying technologies. Besides, as the moisture content of products is reduced, the process temperature is decreased and most of the deterioration and microbiological reactions are also ended. Therefore, both preservation and value-add of high-value food are achieved by using this technology (9), (10). The vacuum freeze-drying consists of two important systems; freezing system and freeze drying system. Freezing required the removal of heat. Ideally, two-component liquid systems, water and solute, are crystallized (6). In order to have freezing operations to be cost-effective, it is necessary to optimally design the efficient refrigeration system. Such a system includes compressor, condenser, evaporator and axial fan (1), (2), (4), (6), (8). The other part of the system, the freeze drying must remove water of product by sublimation process and also involves mass and heat transfer (8). Thus, the refrigeration system must work for both processes appropriately
