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This study describes the results of an experimental investigation of an earth–air heat exchanger for heating and cooling in Patna India, using an experimental test rig. An experimental test rig was constructed and built for the climatic and soil conditions of Patna. In the test rig, three horizontal polyvinyl chloride (PVC) pipes of equal length with a diameter of 0.0285, 0.038, and 0.0485 m were installed. The tests were conducted with ambient air entering at various speeds of 2, 3.5, 5, and 6.5 m/s. The result of the experiments shows that the temperature rises and falls in the larger diametric pipe are lesser than those in the smaller ones, and it decreases slightly as the velocity of air increases. So, a smaller diametric pipe with a lower airflow velocity shows a maximum rise and fall in temperature. The cooling and heating capacity (heat transfer rate) increases with increased inlet velocity. In both heating and cooling applications, the effectiveness of an earth–air heat exchanger decreases as the velocity of the moving air increases. Also, the larger diametric pipe has less effectiveness than the smaller diametric pipe. The maximum heating and cooling effectiveness of 0.63 and 0.61, respectively, was observed for 28.5 mm diameter pipes when the inlet air speed was 2 m/s. [ABSTRACT FROM AUTHOR]

This paper presents the experimental investigation of an earthto-air heat exchanger for heating purposes in the Patna region of India, using an experimental test rig. In the view of the author, real field experiments have several limitations such as lack of repeatability and uncontrolled conditions. It also takes more time for the response of parameters that depends on nature and climate. Moreover, earth-to-air heat exchangers may be expensive to fabricate and require more land area. Thus, in this work authors executed their experimental work in indoor controllable environments to investigate the thermal performance of an earth-to-air heat exchanger. The actual soil conditions were created and maintained the temperature at 26°C throughout the soil in the vicinity of pipes. Three horizontal PVC pipes of equal lengths and diameters of 0.0285 m, 0.038 m and 0.0485 m were installed in the test rig. The experiments were performed for different inlet air velocities at ambient air temperature. This study acknowledges that the maximum rise in outlet temperature occurs at a lower speed for smaller pipes. Also, the maximum effectiveness of 0.83 was observed at 2 m/s for the smallest diameter pipe. [ABSTRACT FROM AUTHOR]

• A thermal–hydraulic model for an SFR SG is created using the FLOWNEX code. • The model uses fixed meshes with regime-specific flow and heat transfer correlations. • Steady-state predictions of the model are validated by inter-code comparison. • Transient predictions of the model are validated against ETEC and SGTF experiments. The steam generator (SG) is an important component in sodium-cooled fast reactors (SFRs). It transfers the heat from sodium systems to the balance of plant (BOP), producing steam for electricity production. Any disturbances originating from the BOP propagate to the nuclear systems through SG. Hence, it is especially important to model and predict the thermal–hydraulic behavior of SG during such transients. Towards this, a thermal–hydraulic model of SG of a typical medium-sized SFR has been developed using general-purpose system simulation code – FLOWNEX. Usually, the moving boundary method is used to model SGs as it involves phase change and multiple heat transfer regimes. However, in the current model, the fixed mesh approach, generally used for modeling pipelines, single-phase heat exchangers, etc. in plant dynamic codes, has been used to model SGs. In this paper, the modeling details and the solution procedures used in the FLOWNEX are discussed in detail. The steady-state results of the model developed have been compared with the results from in-house code DESOPT. The results were in good agreement at various power levels as well as in off-design conditions. The transient performance of the model has been validated against an in-house experiment carried out in Steam Generator Test Facility (SGTF), IGCAR, India, and a steam generator shutdown experiment carried out in Energy Technology Engineering Center (ETEC), Santa Susana Field Laboratory (SSFL), USA. The transient results were also in good agreement, thereby increasing the confidence level of the predictions. The model developed will be integrated to plant dynamic codes containing other system models and will be used to carry out system-level simulations in the future. [ABSTRACT FROM AUTHOR]