Analysis of Energy Exchange with the Ground in a Two-Chamber Vegetable Cold Store, Assuming Different Lengths of Technological Break, with the Use of a Numerical Calculation Method—A Case Study

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).

Numerical Analysis of the Effect of Floor Depression on the Extent of Thermal Interaction with the Ground and Energy Management Using a Vegetable Cold Store as an Example

“…Depending on the specific case, various measures can be taken to minimize energy losses to the ground, particularly in the form of improving the thermal insulation of the zero state [26]. In small refrigeration facilities, very often with no adequate thermal insulation of the floor and foundations, it is necessary to consider the possibility of using the ground as a medium for stabilizing thermal conditions and a kind of cold accumulator [2,3]. The current state of knowledge shows that the contribution of land to the total energy balance of residential and industrial facilities is about 5-10% [27].…”

“…Agricultural refrigeration is designed to extend the shelf life of products, preserve their quality and prevent microorganism growth, which is particularly important for perishable foods [1][2][3]. Refrigeration facilities are buildings equipped with a cooling system that maintains a low temperature, as recommended for the type of products that are stored in them.…”

Numerical Analysis of the Effect of Ground Dampness on Heat Transfer between Greenhouse and Ground

“…A similar approach was used in this study (constant dampness level in the ground profile). The applied WUFI ® plus calculation tool was used repeatedly for non-stationary analyses, taking the coupling between the building and the ground into account [10,27,[30][31][32][33][34].…”

Numerical Analysis of the Impact of the Location of a Commercial Broiler House on Its Energy Management and Heat Exchange with the Ground

“…The location of the building and the prevailing climate primarily determine the energy performance of buildings and the requirements placed on them, from the perspective of thermal protection and energy efficiency [25]. The specific mode of operation of agricultural buildings, especially cyclic use, can be a positive feature in terms of the possibility of technological and functional modifications [14,26,27]. The results of analyzing the influence of location on the energy management of the studied buildings showed that the external climate significantly determined the amount of energy expenditure for heating purposes.…”