High Energy Efficient System Design for Incubation Process and Cooling of Yoghurt

Karaca G., Dolgun E. C., Mavus R., AKTAŞ M.

JOURNAL OF POLYTECHNIC-POLITEKNIK DERGISI, vol.23, no.3, pp.779-784, 2020 (ESCI) identifier

  • Publication Type: Article / Article
  • Volume: 23 Issue: 3
  • Publication Date: 2020
  • Journal Indexes: Emerging Sources Citation Index (ESCI), TR DİZİN (ULAKBİM)
  • Page Numbers: pp.779-784
  • Gazi University Affiliated: Yes


Food processing studies are important for both efficient use of energy and to obtain quality products. Yoghurt is a dairy product which consumes widely. Yoghurt producing facilities consumes high energy and run at low efficiency due to their traditional production methods. In order to produce quality yoghurt, pasteurized milk should be kept at 42-45 degrees C for 3-5 hours depending on the yeast type, this process called as incubation. After the incubation process, produced yoghurt must be cooled down to 20 degrees C in two hours depending on the package size of yoghurt. In conventional yoghurt production facilities, required heating and cooling are applied independently and this approach causes high energy consumptions, waste heat and the inefficient use of energy. In this study, a combined system consisting of a heat pump and a heat storage unit which is capable of the simultaneously heating and/or cooling application independently of each other is designed to ensure higher energy performance and efficiency. Thus, the required energy for heat transfer from the evaporator and cooling after the incubation process was ensured from the stored ice and, independently of the weight of the product, 64/68 units of energy (depending of refrigerant) were gained for each 100 units of required heating energy.The coefficient of performance (COP) of the system using R410a and R134a for heating, cooling and dual operation modes were calculated as 2.83, 1.83, 4.66 and 3.16, 2.16, 5.31, respectively. Energy costs for heat pump and conventional natural gas-fuel-oil boilers were compared. High energy efficiency and low energy consumption have been provided with the presented design, and suggestions for use for production facilities are given.