**Abstract**

The computational fluid dynamic (CFD) is an influential method for measuring Heat transfer profiles for typical meteorological years. CFD codes are managed by numerical algorithms that may undertake fluid glide headaches. CFD offers the numerical results of partial differential equations with main airflow and heat transfer in a discretized association. The complex fluid glide and the warmth transfer publications worried in any heat exchanger can be determined with the help of the CFD software program (Ansys Fluent). A study states and framework which implicitly rely on the computational fluid dynamics, which is being formulated for computing the efficiency-related parameters of the thermal part and the capability of the EATHE system for cooling. A CFD simulation program is being used for modeling the system. The framework is being validated with the help of the simulation set-up. A thermal model was developed to analyze thermal energy accumulated in soil/ground for the purpose of room cooling/heating of buildings in the desert (hot and dry) climate of the Bikaner region. In this study, the optimization of EATHE design has been performed for finding the thermal performance of straight, spiral, and helical pipe earth air tunnel heat exchanger and Heat transfer rate for helical pipe was found maximum among all designs.

**Keywords:** computational fluid dynamic, straight pipe, spiral pipe, helical pipe, heat exchanger for earth to air, design

### **1. Introduction**

The current world scenario facing an energy crisis because of the depletion of fossil fuels, so we are in need to find alternative sources of energy which can satisfy future energy needs. Non-conventional sources of energy are better alternatives that can be found abundantly on earth [1]. Air-conditioning is a commonly used household and industrial appliance for cooling. The common working fluids used in these devices are CFCs are hazardous to human beings and depletes the ozone layer of the atmosphere. Alternative refrigerants are developed by scientists to overcome the problems associated with energy consumption, environmental pollution, and performance [2, 3]. In this regard one of the alternatives is EATHE. EATHE are modern devices in which tubes are buried under the earth at 1.5 m to 2.5 m. the temperature will remain constant at this depth and it is equal to the annual average temperature. The constant temperature will remain lower in summer and it can be utilized for cooling, similarly, it can be utilized for heating in winter conditions. EATHE is made up of metallic, concrete, or plastic tubes which are buried under the earth which can utilize the heat capacities of the earth for heating and cooling conditions. TEATHE is used as a source in the winter and sink in the summer. EATHE can be effectively used as a cooling system if the cooling load requirements are met or else it can assist the cooling systems by saving an enormous amount of energy. Many researchers have found out that EATHE can reduce energy consumption enormously and it can be used for building heating and cooling conditions [4–6]. The important factors which affect the performance of the EATHE system are surface condition, temperature, and moisture [7]. Earth to air heat exchanger model has been developed for calculating thermal performance in cooling mode and CFD model is compared with experimental data, 6.07% variation have found while comparing outlet temperature of earth pipe air heat exchanger in CFD model and experimental setup. This variation may be due to the coefficient of friction of the material which is used in simulation taken, irregularities such as insulation, and joints of experimental set-up [8]. CFD model of different diameters of chlorinated polyvinyl chloride pipes has been used for finding thermal performance of heat exchanger for the earth to air in a cooling mode where temperature fall has reduced while decreasing pip diameter and vice versa [9]. In this work, the CFD model of the earth air pipe heat exchanger has been used for finding thermal performance for building heating and cooling purposes. Temperature fall has occurred in cooling mode is 18.590 C and while heating mode, the temperature rises 12.8°C [10]. In this work, the CFD model was validated with an experimental setup where a maximum variance of 7% between the experimental and simulation results is founded [11]. CFD model of different diameter of chlorinated polyvinyl chloride pipes has used for finding thermal performance of heat exchanger for earth to air in cooling mode where temperature fall has reduced while decreasing pip diameter and vice versa [12].
