Abstract-In the current study, research on the performance characteristics of an adsorption cooling system supplied by solar energy is presented. The main task for the analyzed system was to ensure cooling load for the non-residential building in cold climate country. A 8.0 kW adsorption thermal cooling system was studied. The system got heat produced by evacuated tube solar collectors. The parametric simulation study was carried using a TRNSYS (Transient Systems Simulation) program to determine the influence of various parameters on the system performance. The dependencies of collector slope and the total absorber area on solar fraction, discarded energy, coefficient of performance, seasonal performance factor were studied. The highest solar fraction, coefficient of performance and seasonal performance factor values were obtained if the collector slope was approximately 30 degrees and the absorber area was 16 m 2 for the analyzed cases. The total primary energy consumption of the system was examined for various cases of primary energy factor for auxiliary heat and consumed electricity. On the basis of the results, it was proposed the expression of total primary energy consumption. The obtained results could be used for the recommendation preparations for decision makers to select a small scale solar cooling adsorption system.
Abstract-In near zero energy buildings (NZEB) built in Baltic countries, heat production systems meet the challenge of large share domestic hot water demand and high required heating capacity. Due to passive solar design, cooling demand in residential buildings also needs an assessment and solution. Heat pump systems are a widespread solution to reduce energy use. A combination of heat pump and solar thermal collectors helps to meet standard requirements and increases the share of renewable energy use in total energy balance of country.The presented paper describes a simulation study of solar assisted heat pump systems carried out in TRNSYS. The purpose of this simulation was to investigate how the performance of a solar assisted heat pump combination varies in near zero energy building. Results of three systems were compared to autonomous (independent) systems simulated performance. Different solar assisted heat pump design solutions with serial and parallel solar thermal collector connections to the heat pump loop were modelled and a passive cooling possibility was assessed. Simulations were performed for three Baltic countries: Lithuania, Latvia and Estonia.
abstract. Heat pump systems are promising technologies for current and future buildings and this research presents the performance of air source heat pump (ASHP) system. The system was monitored, analysed and simulated using TRNSYS software. The experimental data were used to calibrate the simulation model of ASHP. The specific climate conditions are evaluated in the model. It was noticed for the heating mode that the coefficient of performance (COP) varied from 1.98 to 3.05 as the outdoor temperature changed from -7.0 ºC to +5.0 ºC, respectively. TRNSYS simulations were also performed to predict seasonal performance factor of the ASHP for Vilnius city. It was identified that seasonal performance prediction could be approximately 15% lower if frost formation effects are not included to air-water heat pump simulation model.
In order to reduce impact to environment, a qualitative approach of energy saving is global aspect that is included in various forms of CO2 emissions, primary energy limitations and benchmarks in EU and member countries policy. Exergy analysis allows expressing the quality of energy flows in comparison to ambient or other reference conditions. Despite of this valuable information, this concept is not widely used in engineering practice. The article suggests the calculation procedure for sessional or periodical thermodynamic (exergy) efficiency in relation to variable reference conditions. Knowledge about defined procedures unlocks the possibility to fill up the implementation gap for building system engineering practice where seasonal performance parameters are widely used to express efficiency. Prepared algorithm allows determining seasonal or periodic thermodynamic efficiency of individual elements and energy transfer chains in building energy systems. Defined calculation procedure workflow is suitable for integrated approach when coupled heat transfer and fluid flow processes are explored in short time steps with dynamic simulation software tools. Presented algorithm ensures result that fits in thermodynamically correct range 0-1 and helps to summarize separate time step results. By adding duration of specific conditions, this analysis enables to identify critical peak periods and base load conditions across operation period. The presented framework fills the gap in lack of systematic expression for seasonal thermodynamic efficiency and suggests the process for calculation procedures workflow.
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