Design and Fabrication of Solar-Powered Portable Thermoelectric Refrigeration System for Thermolabile Pharmaceuticals

Abstract

In order to maintain the therapeutic efficacy of thermolabile medicine and vaccines, electrical energy must be continuously supplied. For remote areas lacking access to electrical electricity, this poses a serious dilemma. The potency level of thermolabile medications and vaccines is decreased, particularly during last-mile delivery, which causes significant financial loss. In this study, we designed and developed a portable active refrigeration system that runs on solar photovoltaic cells for the refrigeration of thermolabile pharmaceuticals to be utilized in rural areas without access to electricity, especially to facilitate last-mile vaccination delivery. The system makes use of a thermoelectric refrigeration system that, when given electrical power, causes a temperature difference based on the Peltier effect. It will be demonstrated that a solar panel with a peak power of roughly 50W and batteries with a storage capacity of 10Ah are needed for a typical application for vaccine refrigeration. The developed refrigeration system has a 3-liter volume capacity and can store 150 vaccine ampules, each with a 10ml capacity, at temperatures between 2°C to 8°C using a Peltier cell (TEC), that consumes 66 W at 12V

Introduction

I. INTRODUCTION

Any nation must have access to basic healthcare, especially if it wants to improve circumstances for its citizens and ensure that infants survive. Vaccinations are given out as one of the basic medical services in this regard.

The percentage of people worldwide who have received the DTP-31 vaccine has increased to 78% [1], saving more lives and preventing more disease outbreaks. If the administered vaccines are not effective at the time of usage, the effect of this expanded coverage will be muted. The enormous effort made to reach children with immunization services will be in vain if vaccines are stored carelessly and suffer temperature-related harm. The inadequacy of the current cold chain in many nations is a result of improperly maintained or antiquated refrigerated equipment, poor adherence to cold chain protocols, insufficient monitoring, and a lack of awareness of the risks associated with vaccine freezing [2].

The majority of vaccinations are considered to be thermolabile products. Thermolabile medications are those that need certain storage conditions and often demand low temperatures (between 2 and 8 degrees Celsius). If these requirements are not met, the properties of these medications may deteriorate to varying degrees depending on the temperature attained and the time spent there. If the medication has already been given to the patient, this either entails a financial loss or therapeutic inactivity [3].

The logistics required to ensure temperatures between 2 and 8 °C from production to final administration for thermolabile medications is known as a "cooling chain" [4]. Refrigeration systems are essential for this purpose, which calls for continuously given electrical energy. However, in many developing nations, conventional electrical energy distribution systems have fallen short in terms of accessibility and dependability to meet the needs of rural health clinics [5].

Solar energy is a clean, non-polluting, renewable energy source that has been increasingly appealing over the past ten years for uses like cooling vaccines and medications in remote areas of developing nations. Thus, in this study, we design and construct a mobile active refrigeration system that uses solar photovoltaic cells to cool thermolabile drugs in rural areas utilizing thermoelectric refrigeration systems. Thermoelectric cells (TEC) have been developed over the past few decades to efficiently convert electrical energy into a heat flow (cooling). When electrical energy is applied to the junction of two distinct materials, the Peltier effect is used to create a temperature difference. Thermoelectric refrigerators have already been utilized for commercial and industrial goods as well as for instrumentation in the military and aerospace [6].

Other authors have already studied thermoelectric coolers [7, 8], but in this work, we combine the design and development of the thermoelectric refrigerator with the photovoltaic system to achieve a self-sustaining cooling system without emitting greenhouse gases, as well as without the noise and maintenance issues typically associated with conventional refrigeration systems.

II. SYSTEM CONFIGURATION

The proposed refrigeration has three electrical energy sources. If we have 240 volts of ac power, we can connect the refrigeration directly by using an SMPS (switch mode power supply) to convert 240 volts to 12 volts. If we don't have power, we can use batteries to power Peltier modules or solar panels to charge batteries, which in turn provide the necessary DC energy to the thermoelectric refrigerator. The thermoelectric refrigerator has a 3-liter overall capacity and is designed to hold about 150 vaccine ampules, each with a 10ml capacity. A Peltier cell, which utilizes the electrical energy from the module, provides cooling.

We employed a wooden frame design to keep the cabin box cold, and a cooling chamber that is highly insulated with polyurethane foam and glass wool for thermal isolation from the surroundings. The storage chamber features a thin layer of aluminium foil for even temperature distribution and is equipped with a phase change material (PCM) to lessen thermal fluctuations during logistics. A closed-loop electronic control system is employed to keep the temperature firmly between 2°C and 8°C and a heat sink is used to reject heat to the atmosphere. End users can record and view the cabinet temperature in real-time on a temperature monitoring display. The overall thermoelectric system's energy flow is shown in Fig. 1.

Conclusion

In this research, a functional prototype of a thermoelectric refrigeration system was successfully developed. The 2°C to 8°C storage temperature range, which is essential for keeping insulin stable, was successfully attained by the device. The system was built with operational settings that would shut down at 2°C and start up again at 8°C. The system\\\'s cooling performance was evaluated, demonstrating a temperature reduction of approximately 5°C within approximately 34 minutes in indoor settings, and a temperature reduction of 7°C within around 42 minutes under outdoor conditions. The system may operate independently for up to 2 days due to the integrated batteries, which are designed for a 12 V TEC (Peltier cell) type TE1-12706 with a 66 W total power consumption. With the ability to efficiently draw heat from a 3-liter refrigerator section, this particular TEC module has enough room to hold 150 thermolabile vaccine ampules, insulins, or medications. The innovation is prepared for implementation in isolated rural locations lacking in electrical infrastructure. Thus, storing vaccines/ medications at an effective temperature to help improve the logistic chain, by accelerating access to immunization.

References

[1] Global Immunization Vision and Strategy (GIVS). Facts and figures, April 2005. http://www.who.int/vaccines/GIVS/english/Global imm. data EN.pdf. [2] Protocol for evaluating freezing in the vaccine cold chain. Program for appropriate technology in Health, April 2003. [3] R. Cobos, P. Salvador, A. Gómez and M. Boj, \\\"Estabilidad máxima de los medicamentos termolábiles fuera de nevera,\\\" Farmacia Hospitalaria, vol. 30, no. 1, pp. 33-43, 2006. [4] L. Parraga, A. Gómez-Lobón, I. Gamón, R. Seco, O. Delgado and F. Puigventos, \\\"Thermolabile drugs. Operating procedure in the event of cold chain failure,\\\" Farmacia Hospitalaria, vol. 4, no. 35, pp. 190.e1-190.e28, 2011. [5] Jimenez and K. Olson, \\\"Renewable Energy for Rural Health Clinics,\\\" Renewable Energy for Rural Health Clinics, vol. 1, no. 1, pp. 1-40, 1998. [6] Huang, C. J. Chin and C. L. Duang, \\\"A design method of thermoelectric cooler,\\\" International Journal of Refrigeration, vol. 23, pp. 208-218, 2000. [7] R. L. Field, \\\"Photovoltaic/Thermoelectric refrigerator for medicines storage for devoping countries,\\\" Solar Energy, vol. 25, pp. 445-447, 1980. [8] P. K. Bansal and A. Martin, \\\"Comparative study of vapour compression thermoelectric and absorption refrigerator,\\\" International Journal of Energy Research, vol. 24, pp. 93-107, 2000. [9] R. J. Buist, \\\"Universal thermoelectric design curves,\\\" 15th Intersociety Energy Conversion Engineering Conference, 1980. [10] F. L. Tan and S. C. Fok, \\\"Methodology on sizing and selecting thermoelectric cooler from different TEC manufactures in cooling system design,\\\" Energy Conversion and Management, vol. 49, no. 6, pp. 1715- 1723, 2008.

Copyright

Copyright © 2023 Rutvik Mehenge, Aksh Patel, Pathan Shahidkhan. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.