Abstract
The paper deals with the impact of the technological break duration during the cold storage cycle on the energy demand of the cold store for vegetables and fruit and the temperature distribution in the ground under the cold store. The studied facility was a two-chamber vegetable cold store located in southern Poland used to store carrots (Daucus carota) for nine months a year. The experiments were conducted for 12 months (01.05.2017–30.04.2018). The technological break during this period lasted three months (from 1 July 2018 to 30 September 2018). Continuous measurements (with 1-h frequency) were made in order to determine the boundary conditions for numerical analysis. The measured parameters included indoor air temperature, outdoor air temperature, ground temperature under the building and in its vicinity. There were 22 measuring points andPT100 sensors were used. The numerical analysis was based on the elementary balances method. WUFIplus® software was used as a calculation supporting tool. The numerical analysis was conducted for 14 calculation variants, with different duration of technological break. The calculation model validation was performed and the results showed a good correlation with the experimental data. The results of experimental studies and of calculations showed a significant impact of the technological break duration on the soil distribution in the ground and the building energy demand. A technological break of less than 4 weeks is the most optimal in the summer. The technological break longer than 4 weeks significantly affects the cooling energy demand in the first days of the cooling cycle and significantly extends the time necessary for the ground and the floor to reach the optimum temperature. The analysis of the floor temperature results (points A1–C1) showed that the technological break longer than four weeks causes the average floor temperature to exceed 4.0 °C. Therefore, the optimum solution is technological break lasting 7–35 days. Absence of technological break results in a decrease of energy gains from the ground by 20% relative to a three-month technological break. The impact of technological break duration was clearly seen in terms of energy losses from the cold store to the ground. In case of a 91-day technological break, the energy losses to the ground were 1289.5 kWh/a, while in case of absence of technological break this value was ninefold lower (147.5 kWh/a).
Highlights
In order to preserve the suitable commercial nutritional and biological quality, the vegetables and fruit should be stored at a specific temperature and humidity, with appropriate gas composition and Energies 2020, 13, 4970; doi:10.3390/en13184970 www.mdpi.com/journal/energiesEnergies 2020, 13, 4970 lighting [1,2]
The results of experimental studies and of calculations showed a significant impact of the technological break duration on the soil distribution in the ground and the building energy demand
The average outdoor air temperature during the experimental studies conducted from 1 May 2017 to 30 April 2018 was 9.4 ◦ C
Summary
In order to preserve the suitable commercial nutritional and biological quality, the vegetables and fruit should be stored at a specific temperature and humidity, with appropriate gas composition and Energies 2020, 13, 4970; doi:10.3390/en13184970 www.mdpi.com/journal/energiesEnergies 2020, 13, 4970 lighting [1,2]. The appropriate storage is to reduce the intensity of microbiological, chemical and biological processes that usually cause a deterioration of the quality of stored products [3,4]. The optimization of conditions in storage chambers is based on automation which controls the airflow, heat flow and monitors the mass exchange on a current basis. These are linked processes, that is why attempts are being made to improve the mathematical models which to a significant degree facilitate understanding the processes taking place in cold stores. The intensity of the heat exchange with the ground during the technological break is the main factor affecting the cooling energy demand in the storage cycle. Numerous results of studies conducted by many authors on the heat exchange with soil should be used in order to estimate the optimum duration of the technological break which will ensure the lowest possible energy demand
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
