Energy simulation and CFD coupled analysis for the optimal operation of combined convection and radiant air conditioning considering dehumidification

The use of radiant panels in homes has increased recently because they do not cause a drafty feeling, unlike air conditioners. However, air conditioners are more power-efficient than radiant panels and have a higher coefficient of performance (COP). Therefore, combining radiant panels and air conditioning can provide an optimal solution for thermal control in residences. Energy simulation (ES) and computational fluid dynamics (CFD) can be used to simulate such environments. ES is suitable for non-steady state calculations, and combined with appropriate modeling, enables an accurate estimation of power consumption. Effective dehumidification becomes necessary, during summer as the relative humidity in a room increases. Both air conditioners and radiant panels can achieve this. This study developed a simulation tool that incorporates the effects of dehumidification. Based on a relative evaluation, a case was proposed where both energy efficiency and comfort were satisfied by jointly using air conditioners and radiant panels. The study found that a small number of panels could achieve the most balanced operation. The results of this study can serve as a reference for general housing, and the developed simulation tool can be applied to product development and building material design.

Energy simulation modeling for water-energy-food nexus system: a systematic review

Since essential nexus variables were not considered in the energy subsystem, this study focused on the role of energy in the Water, Energy, and Food nexus (WEF nexus) system. The energy subsystem interacts with water and food on the supply and demand sides. The WEF nexus-based energy model has not been reviewed recently. This study provides a systematic review of 459 articles regarding energy simulation modeling issues relating to the WEF nexus system. The keyword ("energy" AND "simulation" AND "nexus") as well as "water" OR "food" OR "climate" OR "land" OR "carbon" OR "environment" is used for searching WEF nexus documents for energy simulation. The review highlighted that the energy subsystem is modeled online (One-way) and offline (Two-way), and the energy simulation struggles to represent its system boundary with the water and food subsystems in different spatial scales (household to global). The energy subsystem of the WEF nexus did not address return flow from cooling towers and crop energy consumption comprehensively. In the research, the supply and demand section of the energy subsystem demonstrated that a comprehensive simulation model for energy can be developed using the nexus system approach. The energy subsystem's supply, primarily power plants, interacts with the water subsystem, and the energy generation policy is based on water use. The WEF nexus system assesses renewable energy effects to reduce tradeoffs. In addition, energy demand is related to energy consumption, so the energy consumption for each crop can be calculated and explained the appropriate cultivation pattern based on it.

Simulating energy consumption based on material addition rates for material extrusion of CFR-PEEK: a trade-off between energy costs and cycle time

While many studies for material extrusion-based additive manufacturing (AM) of polymers focus on experimental approaches to evaluate relevant performance measures from process parameters, there is a lack of discussion to connect experimental results with useful applications. Also, one of the major deficiencies in the application literature is a trade-off analysis between energy costs and cycle time (time to produce an item from the beginning to the end) since improving these two measures simultaneously is challenging. Thus, this paper proposes an energy simulation method for performing a trade-off analysis between energy costs and cycle time using combinations of major AM process parameters for material extrusion. We conduct experiments using carbon fiber-reinforced poly-ether-ether-ketone (CFR-PEEK), which is increasingly used in material extrusion. From experimental results, we build a power model in which power (kW) is derived as a linear function of material addition rates (MAR). This MAR regression model is then used in a proposed simulation model that integrates discrete event simulation and numerical simulation. In our simulation case study of 50 machines and 40 scenarios, we investigate trade-offs between energy costs and cycle time with three control policies (P₁, P₂₅, and P₅₀) that allow 1, 25, or 50 machines to start heating, respectively. The trade-off analysis results show that P₂₅ can be preferred when a balance between cycle time and energy costs is pursued, while P₁ or P₅₀ can be chosen if either energy cost (with P₁) or cycle time (with P₅₀) is more important than the other measure. Moreover, we find that the machine utilization, variability, and product volume have significant effects on energy costs and cycle time.

Potential for retrofitting a federal building in the UAE to net zero electricity building (nZEB)

Demand Side Management of the building sector has attracted great attention in the United Arab Emirates (UAE). However, the challenge lies in the existing buildings that form the majority of the built environment. Therefore, retrofitting the existing stock has become a priority and many initiatives have emerged to speed up the pace within the retrofit market. This paper aims to assess the potential of retrofitting an existing federal office building to a net zero electricity building through a holistic retrofit approach. Several passive and active measures are implemented in order to achieve this goal including the integration of different grid-connected photovoltaic (PV) systems.

The commercially available Integrated Energy Solution – Virtual Reality (IES-VE) building energy simulation software is used to evaluate the impact of all the implemented strategies on reducing electricity consumption in order to highlight the optimal scenario prior to introducing the PV systems. In this particular study, the implementation of active measures has proven to be more effective in reducing energy demand than passive measures. The passive strategies reduced electricity demand by 14.7%, whilst active measures reduced electricity demand by 63.2%.

A PV system was able to cover the reduced energy demand resulting in a net Zero Electricity Building (nZEB).