## 2 Literature Review
### SHTES Systems in Greenhouses
#### 2.2.3 Rock Bed as SHTES System
The findings revealed that, with fewer  
Figure 27:0 The schematics of the proposed system by [PERSON] et al. [52]. variations and fluctuations, the air temperature in the greenhouse with SHCS was higher than that of the simple one by around 3 \({}^{\circ}\)C at night and 6 \({}^{\circ}\)C during the day. In addition, the relative humidity dropped by 10% at night. The tomato yield was 1.74 kg\(\cdot\)m\({}^{-2}\) higher with SHCS than it was with regular production. [PERSON] et al. [55] concentrated on the possibilities for greenhouse farming in arctic regions (circumpolar territories). Their work considered a case study in Nunavik, Quebec's  
Figure 27:1 The schematics of the proposed system by [PERSON] et al. [53]. northern Inuit region (the Kuujiuaq cooperative greenhouse). The primary issue with greenhouses in Nordic climes, particularly in winter, is the excessive temperature differential between day and night, inhibiting crop growth. In October 2018, they planned, constructed, and deployed a heat storage system to mitigate this thermal behaviour. Based on rock bed thermal inertia, the TES system is a hybrid of an active and a passive system. The schematics of the proposed system by [PERSON] et al. [55] are demonstrated in Figure 27:2  
Figure 27:3 The schematics of the proposed system by [PERSON] et al. [55]. In the active system, the rocks lie under the cultivated soil. Therefore, no ground excavation is required. Based on the Tichelmann principle, the active system's air distribution system arranges the pipes so that air flows through each segment of the storage system for the same period. Each of the four sections that made up the greenhouse had a separate system known as a \"cailsson\". Roughly \(1\times 10^{4}\) kg of rocks with grain sizes ranging from 0.01 m to 0.05 m are included in each caisson. A fan at the top of the greenhouse draws air into the system and then disseminates it through a blocked pipe with a perforation in its embedded section. The air is collected by another perforated tube after exiting the caisson and released into the bottom section of the greenhouse. The ventilation mechanism keeps the warm air at the top of the greenhouse from being expelled outdoors throughout the day and blows it into the caisson's colder rocks. This is the TES system's charging phase, which warms the rocks and simultaneously cools the greenhouse air. In contrast, by forcing air into the heated rocks at night, the operation will warm the air within the greenhouse. In addition to this convective heat transfer, conductive heat transfer from the rock stock keeps the cultivated soil at an ideal temperature for plant growth. Lastly, it is essential to note that the active TES system is connected to a passive storage system consisting of a concrete floor slab and rocks between 0.05 and 0.2 m enclosed in gabion baskets. Their outcomes presented that the first need to reduce the difference in temperature between day and night inside the greenhouse is fulfilled by the combination of passive and active thermoelectric sensors. It is possible to keep the lowest temperature above \(10\)\({}^{\circ}\)C for most of the growth season using the suggested TES system. Considering the amount of power used for both the charging and discharging phases, the system's coefficient of performance (COP) ranges from 1.4 to 3. It should be mentioned that during the start of the growth season, the stored energy makes up between 6.2% and 10.6% of the solar energy available within the greenhouse. [PERSON] et al. (2016) employed computational fluid dynamics (CFD) models to simulate the microclimate in a greenhouse with a rock bed heating system. Crop rows and rock bed blocks were deemed porous mediums because of their dynamic and thermal properties. The model's correctness was validated by comparing simulated and experimental greenhouse climatic parameter data. The model's ability to forecast temperature, humidity, and air velocity fields in the greenhouse and rock bed systems was proved during energy storage and restitution.