• Journal of the Korean housing association
• /
• v.13 no.6
• /
• pp.89-99
• /
• 2002

The purpose of this research is to analyze the characteristics of flow rate distribution in hot-water piping networks in the apartment building. A 14-story apartment house was selected as a sample building and analyzed numerically by Hardy-Cross method. Two different piping networks, one has three vertical zones and the other of a single zone with automatic balancing valves, were compared. Some of research results are as follows; As the temperature of supply hot-water increases, the flow rate of it does by buoyancy effect, but this effect is not found in the piping network with automatic balancing valves. Non-uniformity in hot-water flow distributions to all stories in the piping system of single vertical zone can be completely reformed by the installation of either manually operated or automatic balancing valves in every story.

• Journal of the Korean housing association
• /
• v.19 no.5
• /
• pp.111-120
• /
• 2008

The aim of this study is to present the design methods about manifold location being installed and size and to draw out the proper piping size as comparing the fluctuation of discharge with manifold size and residence size through the piping network analysis, when using the same faucet in accordance. The findings are summarized as follows, 1) an appropriate header main body pipe diameter was deemed to be $32{\sim}50\;mm$. 2) the research presented design measures for the application of appropriate water supply inlet pipe diameters according to residential buildings with various sizes. 3) the header direct branch piping method is ideal for small and medium-sized residential complexes, and the header branching and semi header methods are deemed to be more favorable for large residential complexes. 4) this study offered design measures for appropriate header system main body pipe diameters, water supply inlet pipe diameters, header system piping methods, application methods for functional auxiliary equipment units, and header system installation spaces and location.

• Journal of Advanced Marine Engineering and Technology
• /
• v.11 no.1
• /
• pp.39-52
• /
• 1987

Recently, the design problem of heat insulation have been reappraised in the aspect of energy saving due to the rising trend of energy cost. For example, that design problem is increasingly requsted in the fields of accommodation air conditioning systems, hot water supply systems, cargo handling systems, district heating or cooling systems. The rational design of heat insulation of piping systems can not only improve the overall efficiency of energy transfer but also give energy saving. In this paper, the heat insulation problem of district heating systems is therefore modeled as the multi-stage decision processes, suitable for dynamic programming technique. And take the object function as the sum of heat insulation material cost involved construction cost and heat loss cost, and propose the design method to minimize the object function for overall piping systems by dynamic programing. Effectiveness of design method presented here is proved by a computer simulation.

• Journal of Energy Engineering
• /
• v.22 no.3
• /
• pp.302-306
• /
• 2013

A simple method for balancing flow rates in arrays of parallel connected flat plate solar collectors has been developed. The method is based on a computer program which solves for the flow rate through each of the collectors in a reverse return plumbed array. The analysis uses conventional "K-value" techniques and assumes the effects of density variations within the system to to be negligible. It has been found that by appropriately sizing the inlet and outlet manifolds, flow maldistribution can be nearly eliminated without resorting to expensive or complicated balancing techniques.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.4 no.2
• /
• pp.1-6
• /
• 2008

Very High Temperature Gas Cooled Reactor (VHTR) has been selected as a high energy heat source for nuclear hydrogen generation. The VHTR can produce hydrogen from heat and water by using a thermo-chemical process or from heat, water, and natural gas by steam reformer technology. A co-axial double-tube primary hot gas duct (HGD) is a key component connecting the reactor pressure vessel and the intermediate heat exchanger (IHX) for the VHTR. In this study, a preliminary design analysis for the primary HGD of the nuclear hydrogen system was carried out. These preliminary design activities include a determination of the size, a strength evaluation and an appropriate material selection. The determination of the size was undertaken based on various engineering concepts, such as a constant flow velocity model, a constant flow rate model, a constant hydraulic head model, and finally a heat balanced model.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.21 no.6
• /
• pp.451-465
• /
• 1992

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.29 no.4
• /
• pp.185-194
• /
• 2017

Currently, in comparison with other architectural estimations, the estimation work regarding building mechanical-service systems is time-consuming, and the process is continuously becoming more difficult because of the increased usage of the attached piping materials such as fittings and hangings in addition to their complicated construction processes. To improve this problem, the Korean authority provides a simple estimation method for the attached-material rate regarding the main piping material, which is the most time-consuming work in the architectural-mechanical estimation. However, to be an applicable method on construction sites, a proper conversion rate of the attached-piping material is still required for the proposed method regarding building usage and working types. Therefore, the purpose of this research is the calculation of the rate of the attached-piping materials such as the fittings and supports through the building of the mechanical-service work types of mechanical rooms, air conditioning, domestic water and hot-water supplies, and the drain-, vent-, and gas-piping work in office buildings that have been designed after 2010.

• Journal of the Korean Solar Energy Society
• /
• v.27 no.3
• /
• pp.45-54
• /
• 2007

For a conventional natural-circulation type solar water heater, the pressure head is limited by the height between the storage tank and hot water tap. Therefore, it is difficult to provide sufficient hot water flow rate for general usage. This study deals with a design modification of the storage tank to utilize the tap-water pressure to increase hot-water supply Based on fluid dynamic and heat transfer theories, a series of modeling and simulation is conducted to achieve practical design requirements. An experimental setup is built and tested and the results are compared with theoretical simulation model. The storage tank capacity is 240 l and the outer diameter of piping was 15 mm. Number of tube turns tested are 5, 10, and 15. Starting with initial storage tank temperature of $80^{\circ}C$, the temperature variation of the supply hot water is investigated against time, while maintaining minimum flow rate of 10 1/min. Typical results show that the hot water supply of minimum $30^{\circ}C$ can be maintained for 34 min with tap-water supply pressure of 2.5 atm, The relative errors between modeling and experiments coincide well within 10% in most cases.

• Solar Energy
• /
• v.18 no.2
• /
• pp.51-67
• /
• 1998

In this paper, various solar systems are introduced according to usage pattern considering national weather condition and hot water comsumption pattern. First, basic principle and components of solar hot heater are presented, and then operational machanism of various solar hot water systems are presented according to the case of domestic and industrial use with network of piping.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.16 no.1
• /
• pp.22-29
• /
• 2020

In nuclear power plants, there is a risk of thermal fatigue in equipment and piping affecting system soundness because the temperature change of the system accompanies in every operation and shutdown. Therefore, in order to prevent the excess of the fatigue limit during the lifetime of plants, the fatigue limit of each piping material is determined in the designing stage. However, there are many cases where equipment or piping is locally subjected to thermal fatigue that is not considered in the design, resulting in damage to the equipment and piping, and failure during operation. Currently, local thermal fatigue generation mechanisms that are not taken into account in the design stage are gradually being identified. In this paper, the effects of the fluid temperature fluctuations on the piping soundness due to the mixing of hot and cold water, one of the local thermal fatigue generating mechanisms, were evaluated.