Liquid based diurnal thermal storage

A comprehensive study of using thermal energy storage (TES) tank was performed. In this report, the comprehensive literature review of various options of storing thermal energy in buildings was discussed. The objective of the project was to evaluate charging and discharging performance of a storage tank with and without phase change material (PCM) blocks. The general format of the energy balance for the storage tank considering losses, input energy, inlet and outlet mass flow rates, and PCM blocks was developed. Charging performance was analyzed by three different approaches. Initially, constant input thermal energy rate was considered to be delivered to the tank by different heat pumps from 4.5 kW to 9 kW heating capacity. Charging time, phase change process, and stored energy were analyzed under constant thermal energy rate input mode for charging process. Then, the effect of constant coil temperature on charging process was studied and results were compared to previous cases. Also, a solar assisted heat pump was implemented into the model to verify the effect of solar radiation on pre-heating the air for heat pump and how this process improves the overall charging progress of storage tank. Moreover, discharge procedure was discussed to evaluate various discharge modes based on different water draw flow rates. Based on this analyses developing a complete TRNSYS model of the tank is recommended in order to do whole building energy simulation.

Liquid based diurnal thermal storage

A comprehensive study of using thermal energy storage (TES) tank was performed. In this report, the comprehensive literature review of various options of storing thermal energy in buildings was discussed. The objective of the project was to evaluate charging and discharging performance of a storage tank with and without phase change material (PCM) blocks. The general format of the energy balance for the storage tank considering losses, input energy, inlet and outlet mass flow rates, and PCM blocks was developed. Charging performance was analyzed by three different approaches. Initially, constant input thermal energy rate was considered to be delivered to the tank by different heat pumps from 4.5 kW to 9 kW heating capacity. Charging time, phase change process, and stored energy were analyzed under constant thermal energy rate input mode for charging process. Then, the effect of constant coil temperature on charging process was studied and results were compared to previous cases. Also, a solar assisted heat pump was implemented into the model to verify the effect of solar radiation on pre-heating the air for heat pump and how this process improves the overall charging progress of storage tank. Moreover, discharge procedure was discussed to evaluate various discharge modes based on different water draw flow rates. Based on this analyses developing a complete TRNSYS model of the tank is recommended in order to do whole building energy simulation.

Using Calibrated Simulation to Quantify The energy Savings From Residential Passive Solar Design in Canada

Energy savings from passive solar design applied to a typical Canadian house were quantified using calibrated whole building energy simulation. A detailed energy simulation model was created for a research house which represents a typical Canadian tract house with basic passive solar measures. The model was calibrated to measured furnace gas consumption data. Eight design scenarios were evaluated for eight climate locations. Design parameters included increased thermal mass, increased south window area, and high performance windows. In addition, an advanced house scenario was evaluated which featured optimized geometry, a further increase in south window area, high thermal mass, advanced glazing, and no north facing windows. For the typical house predicted solar heating fractions ranged from 20% to 34% with basic passive solar measures, and 35% to 52% for more aggressive passive solar measures. For the advanced house predicted solar fractions ranged from 40% to 69%.

Using Calibrated Simulation to Quantify The energy Savings From Residential Passive Solar Design in Canada

Energy savings from passive solar design applied to a typical Canadian house were quantified using calibrated whole building energy simulation. A detailed energy simulation model was created for a research house which represents a typical Canadian tract house with basic passive solar measures. The model was calibrated to measured furnace gas consumption data. Eight design scenarios were evaluated for eight climate locations. Design parameters included increased thermal mass, increased south window area, and high performance windows. In addition, an advanced house scenario was evaluated which featured optimized geometry, a further increase in south window area, high thermal mass, advanced glazing, and no north facing windows. For the typical house predicted solar heating fractions ranged from 20% to 34% with basic passive solar measures, and 35% to 52% for more aggressive passive solar measures. For the advanced house predicted solar fractions ranged from 40% to 69%.

An Enhanced Vertical Ground Heat Exchanger Model for Whole-Building Energy Simulation

This paper presents an enhanced vertical ground heat exchanger (GHE) model for whole-building energy simulation (WBES). WBES programs generally have computational constraints that affect the development and implementation of component simulation sub-models. WBES programs require models that execute quickly and efficiently due to how the programs are utilized by design engineers. WBES programs also require models to be formulated so their performance can be determined from boundary conditions set by upstream components and environmental conditions. The GHE model developed during this work utilizes an existing response factor model and extends its capabilities to accurately and robustly simulate at timesteps that are shorter than the GHE transit time. This was accomplished by developing a simplified dynamic borehole model and then exercising that model to generate exiting fluid temperature response factors. This approach blends numerical and analytical modeling methods. The existing response factor models are then extended to incorporate the exiting fluid temperature response factor to provide a better estimate of the GHE exiting fluid temperature at short simulation timesteps.

Sensitivity of exhaust-air façade performance prediction to modelling approaches in IDA ICE

Double skin façades are façade technologies that have the perspective of reducing energy use and improving comfort in buildings due to their adaptable nature. Exhaust-air façades offer the possibility to utilize solar energy by recovering heat from the façade cavity. However, the cavity overheating can be detrimental on the summer performance. Predicting performance and optimizing the system during the design phase is a challenge, especially when the cavity-air is integrated into the HVAC system. Whole-building energy simulation (BES) software tools are an adequate tool for calculating whole building performance, although these can have limitations in the accurate replication of complex building elements. The paper analyses the available and applied modelling approaches within a BES tool, and compares the outputs in terms of cavity temperature, horizontal and vertical temperature profiles, and heat flux through the façade. The sensitivity of the results on the modelling approach is evaluated. Results can serve as a guide for practitioners on the selection of the modelling approach for a given task.