Energy For Hot Water Supply Research Articles

Energy efficiency of multi-apartment residential houses with individual heat supply

Centralized hot water systems widely used in Russia and Belarus are characterized by a considerable length and branching which inevitably leads to increased heat losses and to an unstable hydraulic system. The operation of the domestic hot water system in the circulation mode can be characterized by several parameters; one of which is the specific ratio of the cost of thermal energy for heating a cubic meter of hot water. The parameter is often regulated by law in Russia; exceeding this parameter is considered as administrative violation. The aim of the research is to determine the design and actual costs of thermal energy for hot water supply (hot water heating) and their comparison, analysis of the data obtained. The methodology for determining the design and real costs of thermal energy for hot water supply was to study the operation of the hot water supply system of a residential 144-apartment 9-storey building. The research showed that the actual circulating flow rate is much less than the calculated circulating flow rate. The authors note that in order to optimize the standard for heating a cubic meter of water it is necessary to observe the calculated circulation modes. This will require stabilization of the hydraulic systems of both the external and internal networks which is a difficult but feasible task. The research results are supposed to be taken into account when setting up existing hot water supply systems.

ENERGY DEMAND STRUCTURE OF RESIDENTIAL AND COMMERCIAL SECTORS IN THE FURANO AREA IN HOKKAIDO

The realization of an energy-saving and low-carbon society that does not depend on the use of fossil fuels has become necessary due to adoption of the Paris Agreement at COP21. In order to realize an energy-saving and low-carbon society, it is important not only to reduce energy consumption by means such as insulation of buildings and introduction of highly efficiency equipment but also to reduce energy consumption in cities and regions. The aim of this study was to clarify energy demand structure of residential and commercial sectors in the Furano area in Hokkaido. First, we investigated the characteristics and energy consumption of public facilities owned by the municipalities, and we determined the energy consumption rate and monthly fluctuation of energy consumption for each building use. Next, in order to consider the area management by Furano City in the future, we estimated the urban energy demands of residential and commercial sectors and analyzed the spatial distribution characteristics of energy demand, and we clarified the area in which the use of energy in a network is effective. The following results were obtained. 1) A survey of the characteristics of public facilities showed that there were many facilities that had been constructed in the period from 1981 to 1990. Since about 30 years have passed since the construction of those facilities, many facilities will require replacement of equipment in the future. In addition, there were differences between the municipalities in the state of installation of heating equipment and sources of heating and hot water supply. 2) A survey of the energy consumption of public facilities showed that the energy consumption of facilities with hot baths such as public baths and heated pools was particularly large, and the annual energy consumption for hot water supply exceeded the annual energy consumption for heating in some facilities. In these facilities, conservation of energy for hot water supply as well as heating is necessary. The energy consumption rate and monthly fluctuation of energy consumption for each building use were also clarified using energy consumption data for each facility. 3) The urban energy demands of residential and commercial sectors in Furano City were estimated. The annual electricity demand was estimated to be about 210 TJ, and the annual heat demand was estimated to be about 710 TJ. It was found that the annual heat demand was about 3.4-times larger than the annual electricity demand. In addition, the annual heat demand was divided into annual heating demand and annual hot water demand. The annual heating demand was estimated to be about 375 TJ, and the annual hot water demand was estimated to be about 336 TJ, being almost the same. Analysis for different buildings showed that both electricity demand and heat demand were largest for houses throughout the year. Thus, energy conservation in houses is important to reduce energy demand in Furano City. 4) The urban energy demands of Furano City were analyzed in 250 m square areas, and the spatial distribution characteristics of energy demand were clarified. Furthermore, cluster analysis was carried out using heat demand density and heat/power ratio as input data, and the area in which the use of energy in a network would be effective was clarified.

Usage of solar and wind energy for hot water supply of country (cottage) house in natural conditions of absheron

The calculations show that it is becoming possible to generate the powers of wind device and solar water heater approximately up to 4 kVt due to the use of the offered system SWH+WED. Using the developed system for the purposes makes possible, first, to improve the ecological situation in the region for the summer period and secondly, to reduce fuel and electric energy consumption used in the region standard conditions. Usage of solar and wind energy may save fuel, heavy fuel oil and electric power up to the average 15–20 % percent in natural conditions of Absheron. These data were found by us on analyses of common records from statistics of corresponding departments and institutes. The authors have offered and build practically for the first time the SWH + WED system considered for heating the country (cottage) houses in native conditions of Absheron where solar radiation intensity and wind speed are approximately 500–600 Vt/m 2 7–10 m/sec. respectively in the studied period of the year. It may use the developed system effectively for the hot water supply to the residents of this Region. To our opinion, that may save heavy fuel oil and electric power up to 30–35 % percent taking into account negative data of the departments corresponding.

Feasibility study of a district energy system with seasonal water thermal storage

In this paper, performance of three types of district heating/cooling and hot water supply system with natural and unused energy utilization were examined by using system simulation. An area zoned for both commercial and residential buildings was chosen for this study. The first system is the conventional system in which an electric driven turbo chiller and a gas-fired boiler are installed as the heat source. This is considered as the reference system. Two alternative systems utilize waste heat from space cooling and heating. One is designed based on short-term heat recovery and the other employs the concept of an annual cycle energy system (i.e. seasonal heat recovery). All of the three systems use solar thermal energy for hot water supply to the residential zone. The index for evaluation is the coefficient of performance of the overall system, based on primary energy. As a result, it was found that the seasonal storage system could decrease the energy consumption by about 26% and the short-term heat recovery system could decrease it by about 16% compared with the reference system. In designing the heat recovery system, a balance of cooling/heating demand is an important factor. Therefore a sensitivity analysis of performance of the overall system and the seasonal thermal storage for several load patterns was performed. From these results, it was found that if the amount of heating/cooling demand were well balanced, an improvement of energy performance could be achieved and the utilization factor of the seasonal tank would become higher. Furthermore, the volume of the seasonal storage tank could be reduced.