Development of Economic Water Usage Sensor and Cyber-Physical Systems Co-Simulation Platform for Home Energy Saving

In this thesis, two Cyber-Physical Systems (CPS) approaches were considered to reduce residential building energy consumption. First, a flow sensor was developed for residential gas and electric storage water heaters. The sensor utilizes unique temperature changes of tank inlet and outlet pipes upon water draw to provide occupant hot water usage. Post processing of measured pipe temperature data was able to detect water draw events. Conservation of energy was applied to heater pipes to determine relative internal water flow rate based on transient temperature measurements. Correlations between calculated flow and actual flow were significant at a 95% confidence level. Using this methodology, a CPS water heater controller can activate existing residential storage water heaters according to occupant hot water demand. The second CPS approach integrated an open-source building simulation tool, EnergyPlus, into a CPS simulation platform developed by the National Institute of Standards and Technology (NIST). The NIST platform utilizes the High Level Architecture (HLA) co-simulation protocol for logical timing control and data communication. By modifying existing EnergyPlus co-simulation capabilities, NIST’s open-source platform was able to execute an uninterrupted simulation between a residential house in EnergyPlus and an externally connected thermostat controller. The developed EnergyPlus wrapper for HLA co-simulation can allow active replacement of traditional real-time data collection for building CPS development. As such, occupant sensors and simple home CPS product can allow greater residential participation in energy saving practices, saving up to 33% on home energy consumption nationally

Power Load Management as a Computational Market

Power load management enables energy utilities to reduce peak loads and thereby save money. Due to the large number of different loads, power load management is a complicated optimization problem. We present a new decentralized approach to this problem by modeling direct load management as a computational market. Our simulation results demonstrate that our approach is very efficient with a superlinear rate of convergence to equilibrium and an excellent scalability, requiring few iterations even when the number of agents is in the order of one thousand. Aframework for analysis of this and similar problems is given which shows how nonlinear optimization and numerical mathematics can be exploited to characterize, compare, and tailor problem-solving strategies in market-oriented programming

Research on the performance of radiative cooling and solar heating coupling module to direct control indoor temperature

The energy crisis and environmental pollution pose great challenges to human development. Traditional vapor-compression cooling consumes abundant energy and leads to a series of environmental problems. Radiative cooling without energy consumption and environmental pollution holds great promise as the next generation cooling technology, applied in buildings mostly in indirect way. In this work, a temperature-regulating module was introduced for direct summer cooling and winter heating. Firstly, the summer experiments were conduct to investigate the radiative cooling performance of the module. And the results indicated that the maximum indoor temperature reached only 27.5 °C with the ambient temperature of 34 °C in low latitude areas and the air conditioning system was on for only about a quarter of the day. Subsequently, the winter experiments were performed to explore the performance of the module in cooling and heating modes. The results indicated that indoor temperature can reach 25 °C in the daytime without additional heat supply and about a quarter of the day didn't require heating in winter. Additionally, the transient model of the module and the building revealed that the electricity saving of 42.4% (963.5 kWh) can be achieved in cooling season with the module, and that was 63.7% (1449.1 kWh) when coupling with energy storage system. Lastly, further discussion about the challenges and feasible solutions for radiative cooling to directly combine with the buildings were provided to advance the application of radiative cooling. Furthermore, with an acceptable payback period of 8 years, the maximum acceptable incremental cost reached 26.2 $/m2. The work opens up a new avenue for the application mode of the daytime radiative cooling technology

Optimization of a solar air heater with phase change materials: Experimental and ‎numerical study

In this paper, a solar air heater (SAH) with phase change material (PCM)-based energy storage is ‎investigated. Paraffin was placed underneath the absorber plate as the PCM. A transient two-‎dimensional laminar model was used in the Ansys Fluent 17 software to study the effects of different ‎parameters on the performance of the SAH, such as the air mass flow rate, the amount of paraffin, and ‎the thermal conductivity of the paraffin. The performance of the SAH was optimized by considering ‎two objectives simultaneously: thermal energy efficiency and maximum nocturnal temperature ‎difference between the inlet and the outlet of the SAH. To validate the numerical model, a SAH with ‎a 2-cm paraffin layer and the same dimensions as the numerical model was built and tested. The ‎results of the simulation showed good agreement with the experimental results.

OPTIMAL ENERGY MANAGEMENT OF A HYBRID SOLAR WATER HEATING SYSTEM WITH GRID CONNECTION UNDER TIME-BASED PRICING

Published ThesisIn South Africa, 40 to 60% of the total energy of a normal residential building can be allocated to the heating of water. Traditionally, a standard electric storage tank-water heater (ESTWH) has been the main device for residential water heating within the country. However, as a result of the increase in the South African population, economy and living standards have led to an energy shortage, which has resulted in a steadily increasing electricity price. As an attempt to solve this electricity crisis, Eskom, the main electricity supplier, has recently introduced energy management activities such as energy efficiency (EE) and the use of renewable energy (RE) systems. On the one hand, the EE activities consist of reducing the total (overall) energy consumption during all the time periods, while load management (LM) activities aim to reduce the energy consumption during given time periods, such as peak times, when the Eskom grid cannot meet the demand. During peak times, the electricity consumption is charged at higher rates to encourage customers to shift their loads to off-peak and standard periods when the electricity is at a lower cost. This type of tariff is referred to as time-of-use (TOU) electricity tariff. With TOU, customers can therefore reduce their electricity bills by shifting load demands away from the peak time periods. On the other hand, in order to reduce the larger amount of residential peak load demand, renewable energy systems, such as the solar water heater (SWH), was recently introduced and implemented in South Africa as a replacement to the ESTWH. However, it has been observed that SWHs was not continuously meeting the thermal comfort of the users, under certain weather conditions. During winter, for instance, the amount of thermal energy required is greater than that of summer due to the temperature difference of the water that needs to be heated, while the solar radiation in winter is considerably less due to shorter days and the position of the sun with reference to the earth’s location. As a solution to this, the coupling of the SWH with the ESTWH, referred to as hybrid solar water heating (HSWH) system, is nowadays seen as technical and economic feasible option for water heating in South Africa. The system is composed of a solar collector that uses solar radiation to increase the temperature of water and the ESTWH, which stores the hot water. In the case of poor solar radiation, the SWH fails to increase the temperature of water to the comfortable level; therefore, the required temperature is maintained by the ESTWH. However, implementing optimal energy management of the HSWH can help to meet the required thermal comfort level while reducing the electricity cost, even more so when the TOU tariff is implemented. With this in mind, the aim of this work is to develop an optimal energy management model that will improve the operation efficiency of the HSWH. The main objective is to minimize the water heating energy cost from the grid by taking advantage of the TOU electricity tariff, meanwhile maximizing the thermal comfort level of hot water users. Simulations are performed using Matlab software, and the results demonstrate that operating the proposed hybrid system under the developed optimal energy management model reduced the operation cost when compared to a traditional ESTWH. In addition, the comparisons made in lifecycle costs of these systems shows that in the long run, the hybrid system will be the less costly option with a 49 % saving over a project lifetime of 20 years

Crew appliance study

Viable crew appliance concepts were identified by means of a thorough literature search. Studies were made of the food management, personal hygiene, housekeeping, and off-duty habitability functions to determine which concepts best satisfy the Space Shuttle Orbiter and Modular Space Station mission requirements. Models of selected appliance concepts not currently included in the generalized environmental-thermal control and life support systems computer program were developed and validated. Development plans of selected concepts were generated for future reference. A shuttle freezer conceptual design was developed and a test support activity was provided for regenerative environmental control life support subsystems

CDM Potential for Rural Transition in China Case Study: Options in Yinzhou District, Zhejiang Province

This paper aims to examine the potential of the Clean Development Mechanism (CDM) to address energy- related issues during the rural transition process in China, using a case study of quickly urbanizing and industrializing Yinzhou district in coastal Zhejiang province. Yinzhou's per capita GDP reached US$3100 in 2002, three times China's average, and is targeted to achieve$10,000 in 2020. We assess the current energy status of Yinzhou, and provide projections of energy consumption and CO2 emissions up to the year 2020. Energy resource shortages and limited possibilities to obtain coal-fired electricity from national grid illustrate the opening gap between energy supply and demand. We find that Yinzhou's CDM potential is concentrated in efficiency improvement on the demand side. In that context, we suggest to systematically explore the CDM potential in the industrial sector. Projects will have to involve many stakeholders and the necessary local capacity has to be built. These CDM projects can be considered as killing three birds with one stone, namely maintaining continuous economic growth, alleviating local environmental pollution as well as mitigating global climate change.Clean Development Mechanism, China, urbanization, energy efficiency, Environmental Economics and Policy, Q 540, Q 580,

Demand and Storage Management in a Prosumer Nanogrid Based on Energy Forecasting

Energy efficiency and consumers' role in the energy system are among the strategic research topics in power systems these days. Smart grids (SG) and, specifically, microgrids, are key tools for these purposes. This paper presents a three-stage strategy for energy management in a prosumer nanogrid. Firstly, energy monitoring is performed and time-space compression is applied as a tool for forecasting energy resources and power quality (PQ) indices; secondly, demand is managed, taking advantage of smart appliances (SA) to reduce the electricity bill; finally, energy storage systems (ESS) are also managed to better match the forecasted generation of each prosumer. Results show how these strategies can be coordinated to contribute to energy management in the prosumer nanogrid. A simulation test is included, which proves how effectively the prosumers' power converters track the power setpoints obtained from the proposed strategy.Spanish Agencia Estatal de Investigacion ; Fondo Europeo de Desarrollo Regional