## 1 Introduction
A reference [18] carried out a study using tap water as PCM in racks below bare tubes of evaporator, and it was noticed that the product temperature fluctuations were reduced; however, a significant difference was noted in the PCM utilization between the bottom and the top of the refrigerator, indicating that the position of PCM placement was also important. The investigation was also carried out using organic paraffin as PCM [11], where it was found that when PCM was integrated with the evaporator, a 12% reduction was observed in the power consumption, while it reduced by 17% when PCM integration was on both evaporator as well as condenser side. Additionally, this study was conducted with the PCM-inserted heat exchanger, and the experimental results showed the potential of water as PCM to maintain the temperature of air and product even during compressor off-time up to 2 h [19]. Reference [20] assessed the airflow and the temperature distribution inside a cold chamber by CFD analysis, where solar power was used coupled with cooling pads (brine) to obtain 70% grid dependency. Further, study was carried out experimentally and numerically by placing PCM (ice/water) on the wall of the cold room; the results were validated, and the payback period was found to be 4.1 years [21]. Numerical simulation integrating latent heat cold storage for the refrigerated warehouse was implemented for 16 h a day by developing a model in ANSYS where liquid fraction contours were recorded for PCM plates placed on its roof and floor [22]. Although the incorporation of PCM into cold storage is undertaken through various means, as observed from the above studies, the method of its inclusion in terms of placement and orientation remains insufficiently explored. Proper placement and selection of encapsulation material of the PCM in a cold storage unit is vital before detailed heat exchanger design and PCM sizing are taken up. The practical implementation of a prototype with optimal placement and encapsulation se lection can accrue valuable energy savings to marginal farmers for storing their produce for a longer duration without compromising the quality and nutritional value and also experiencing relief from the pressure of selling their products on a day-to-day basis at available prices. The capital cost of existing grid-powered micro-cold stores is in the range of \(2.5\times 10^{5}\) INR/TR (3227.3 USD/TR), which is unaffordable to marginal farmers [23]. The inclusion of PCM into such cold storage is a promising technology that can bring down the capital as well as the running cost [12], which would then reduce the economic stress on low-income farmers. This study investigates the impact of integrating phase change material with micro-cold storage running on a vapor compression refrigeration (VCR) cycle with respect to its placement inside the storage, the selection of material to contain the PCM (PCM heat exchanger), and the temperature distribution profile inside the cold room. A strategy for optimal placement and design of the thermal energy storage unit for a micro cold storage unit with a storage capacity of 500 kg is the major contribution of this study. A numerical analysis has been carried out, and the same has been experimentally validated to adjudge the appropriate position of the PCM heat exchanger. The results of the work emphasize the selection of the PCM and its encapsulation material based on the product to be stored (fruits and vegetables). The results highlight that a temperature difference ranging from 5 to 7 \({}^{\circ}\)C is recommended between the phase change temperature of PCM and the optimal storage temperature advised for the stored product, depending on the material and configuration of the encapsulation containing the PCM. This outcome is important from a horticulture storage perspective owing to the perishable nature of farm produce being stored.