DEVELOPMENT OF A REFRIGERATION SYSTEM FOR THE STORAGE OF FRESH MAIZE

Abstract

Fresh maize is a highly perishable staple food that lacks adequate storage facilities. Fresh maize can lose its sweetness within a day if stored at ambient conditions due to its sugar decomposition which results from respiration and other metabolic reactions. This work aims at designing a refrigeration system to store and preserve the quality of fresh maize for about ten days. The system was designed to store fresh maize above its freezing temperature of -1oC. It was designed to operate at a temperature range between 0 and 2.5 oC and at a relative humidity between 90 and 95%. These conditions were identified as the optimum storage conditions for fresh maize. The cabinet of the refrigeration system was designed to store 13 kg of fresh maize ears at a time. The dimension of 0.65 m by 0.65 m by 0.70m was found to be adequate. The walls were fabricated from mild steel (outside wall), stainless steel (inner wall) and glass wool (insulator). From the design calculation, 1/6 hp compressor, condenser and evaporator were selected with adequate expansion valve and R134a was used as refrigerant. On no load test, the system maintained a temperature of 0oC, a relative humidity range from 90 to 95% after eight hours. And on load tests, a temperature range from 0 to 2.5 oC and a relative humidity range from 90 to 95% were maintained after eight hours. It kept the maize fresh for ten days without noticeable changes in the physical appearance and taste of the maize.