Numerical Investigation on Vertical Generator Integrated with Phase Change Materials in Vapour Absorption Refrigeration System

A model has been established based on numerical calculation to analyze a vertical tube in tube stainless steel generator with forced convective boiling. Refrigerant vapour is generated from the weak refrigerant-absorbent solution takes place in the middle tube of the generator, when hot water through the outer side is used as boiling medium and the pipe arrays inserted is the phase change material containment. This paper shows the results of the TRNSYS modeling and simulation of a solar absorption cooling system under the weather conditions of Chennai in order to partially satisfy the thermal demand of a building room. The maximum hourly thermal load reaches 165 kW. The suggested model operates with concentrating parabolic collectors, a NH3-H2O single effect absorption air-conditioning system, hot water storage with PCM and an external auxiliary boiler. As a result of the method simplifying for the varying climate and different orientation of the components are analyzed. These outcomes show that the prime system could succeed a yearly solar fraction of 0.58.

TRNSYS Modeling of a Linear Fresnel Concentrating Collector for Solar Cooling and Hot Water Applications

In this paper, simulation of a linear Fresnel rooftop mounted concentrating solar collector is presented. The system is modeled with the transient system (trnsys) simulation program using the typical meteorological year file containing the weather parameters of four different cities in Australia. Computational fluid dynamics (CFD) was used to determine the heat transfer mechanism in the microconcentrating (MCT) collector. Ray trace simulations using soltrace (NREL) were used to determine optical efficiency. Heat loss characteristics determined from CFD simulation were utilized in trnsys to assess the annual performance of the solar cooling system using an MCT collector. The effect of the different loads on the system performance was investigated, and from trnsys simulations, we found that the MCT collector achieves a minimum 60% energy saving for both domestic hot water usage and high temperature solar cooling and hot water applications.

Solar Absorption Cooling and Heating System in the Intelligent Workplace

A solar thermal driven absorption cooling and heating system has been installed in Carnegie Mellon University’s Robert L. Preger intelligent Workplace, the IW. The purpose of this solar installation is to investigate the technical and economic aspects of using high temperature solar thermal receivers driving a two stage absorption chiller to cool and heat a building space. The solar system consists primarily of 52 m2 of single-axis tracking parabolic trough solar collectors (PTSC), and a 16 kW double effect absorption chiller driven by either a fluid heated in solar receivers or by natural gas fuel. The receivers convert solar radiation to thermal energy in a heated fluid; the chiller then uses this energy in summer to generate chilled water. In winter, the thermal energy is directly used for heating. A performance analysis was carried out to estimate the conversion efficiency of the PTSC based on mass and energy balances and heat transfer computations programmed in Engineering Equation Solver (EES). The performance of the overall solar cooling and heating for the IW has been programmed in TRNSYS modeling system. This solar energy system has been estimated to provide 38–50% of the cooling and 9–30% of heating energy depending upon orientation, insulation and storage capacity for 245 m2 of space in the IW. Experimental data are now being collected and will be used for validating the solar collector model. The solar system model will be used in interpreting the data yet to be obtained on the system performance. The primary purpose of this research program is the development of systems which reduce the energy requirements for the operation of buildings by a factor of two or greater, and the provision of techniques and tools for the design and evaluation of such systems.

TRNSYS Modeling of the SEGS VI Parabolic Trough Solar Electric Generating System

A detailed performance model of the 30 MWe SEGS VI parabolic trough plant was created in the TRNSYS simulation environment using the Solar Thermal Electric Component model library. Both solar and power cycle performance were modeled, but natural gas-fired hybrid operation was not. Good agreement between model predictions and plant measurements was found, with errors usually less than 10%, and transient effects such as startup, shutdown, and cloud response were adequately modeled. While the model could be improved, it demonstrates the capability to perform detailed analysis and is useful for such things as evaluating proposed trough storage systems.