A Study for Heat-Loss Characteristics of Hot-Water Layer by the Increment of Reactor Power

2012 ◽  
Author(s):  
Young-Chul Park ◽  
Kyoung-Woo Seo ◽  
Hyun-Gi Yoon ◽  
Dae-Young Chi ◽  
Ju-Hyeon Yoon
Keyword(s):  
Heat Loss ◽  
Water Layer ◽  
Reactor Power ◽  
Hot Water

scholarly journals Design and installation of a hot water layer system at the Tehran research reactor

2013 ◽  
Vol 28 (1) ◽  
pp. 18-24
Author(s):  
Sayedeh Mirmohammadi ◽  
Morteza Gharib ◽  
Parnian Ebrahimzadeh ◽  
Reza Amrollahi
Keyword(s):  
Research Reactor ◽  
Cooling Water ◽  
Fission Products ◽  
Water Layer ◽  
Partial Solution ◽  
Time Frame ◽  
Reactor Power ◽  
Hot Water ◽  
Layer System ◽  
Tehran Research Reactor

A hot water layer system (HWLS) is a novel system for reducing radioactivity under research reactor containment. This system is particularly useful in pool-type research reactors or other light water reactors with an open pool surface. The main purpose of a HWLS is to provide more protection for operators and reactor personnel against undesired doses due to the radio- activity of the primary loop. This radioactivity originates mainly from the induced radioactivity contained within the cooling water or probable minute leaks of fuel elements. More importantly, the bothersome radioactivity is progressively proportional to reactor power and, thus, the HWLS is a partial solution for mitigating such problems when power upgrading is planned. Following a series of tests and checks for different parameters, a HWLS has been built and put into operation at the Tehran research reactor in 2009. It underwent a series of comprehensive tests for a period of 6 months. Within this time-frame, it was realized that the HWLS could provide a better protection for reactor personnel against prevailing radiation under containment. The system is especially suitable in cases of abnormality, e. g. the spread of fission products due to fuel failure, because it prevents the mixing of pollutants developed deep in the pool with the upper layer and thus mitigates widespread leakage of radioactivity.

Hot-Water Layer, Heat-Loss Characteristics of an Open-Pool-Type Research Reactor for Reducing the Pool Top Radiation Level

2010 ◽  
Author(s):  
Young-Chul Park
Keyword(s):  
Heat Loss ◽  
Flow Condition ◽  
Research Reactor ◽  
Water Layer ◽  
Hot Water ◽  
Radiation Level ◽  
Downward Flow ◽  
Reactor Coolant ◽  
Reactor Pool ◽  
Pool Type

During an open-pool-type research reactor operation, it is necessary to access the pool top area for un/loading irradiation test pieces by a required irradiation period. However, when the reactor pool top radiation level exceeds the limit of radiation level by the rising of reactor chimney water contaminated by radioactivity due to a natural convection of the pool water, access the reactor pool top area is denied due to the high radiation level. In the case of HANARO, a hot-water layer (HWL, hereinafter) is maintained below a depth of 1.2 m from the top of the reactor pool in order to reduce the radiation level of the reactor pool top area. After a normal operation of the HWL, the pool top radiation level is safely maintained below the limit of the pool top radiation level. For studying more the characteristics of the HWL under a reactor coolant downward flow condition, The HWL heat loss is calculated based on the HANARO HWL calculation model. The HWL heat loss characteristics were reviewed by variations of the HWL temperature, reactor core coolant flow direction, and reactor power. It was confirmed through the results that the HWL heat loss under a reactor coolant downward flow condition was increased by about 20% to 60% over that under a reactor coolant upward flow condition, as per the HWL temperature variation. It was the reason that the HWL bottom convection heat loss was increased by the higher flow rate under a reactor coolant downward flow condition than that under a reactor coolant in an upward flow condition.

scholarly journals Overview of Solutions for the Low-Temperature Operation of Domestic Hot-Water Systems with a Circulation Loop

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3350
Author(s):  
Theofanis Benakopoulos ◽  
William Vergo ◽  
Michele Tunzi ◽  
Robbe Salenbien ◽  
Svend Svendsen
Keyword(s):  
Low Temperature ◽  
Heat Loss ◽  
District Heating ◽  
Heating System ◽  
Hot Water ◽  
Heating Power ◽  
Circulation Loop ◽  
Space Heating ◽  
District Heating System ◽  
Domestic Hot Water

The operation of typical domestic hot water (DHW) systems with a storage tank and circulation loop, according to the regulations for hygiene and comfort, results in a significant heat demand at high operating temperatures that leads to high return temperatures to the district heating system. This article presents the potential for the low-temperature operation of new DHW solutions based on energy balance calculations and some tests in real buildings. The main results are three recommended solutions depending on combinations of the following three criteria: district heating supply temperature, relative circulation heat loss due to the use of hot water, and the existence of a low-temperature space heating system. The first solution, based on a heating power limitation in DHW tanks, with a safety functionality, may secure the required DHW temperature at all times, resulting in the limited heating power of the tank, extended reheating periods, and a DH return temperature of below 30 °C. The second solution, based on the redirection of the return flow from the DHW system to the low-temperature space heating system, can cool the return temperature to the level of the space heating system return temperature below 35 °C. The third solution, based on the use of a micro-booster heat pump system, can deliver circulation heat loss and result in a low return temperature below 35 °C. These solutions can help in the transition to low-temperature district heating.

Evacuated Tube Heat Pipe Solar Collectors Applied to Recirculation Loop in a Federal Building: SSA Philadelphia

Solar Energy ◽  
2004 ◽  
Author(s):  
Andy Walker ◽  
Fariborz Mahjouri ◽  
Robert Stiteler
Keyword(s):  
Solar Energy ◽  
Heat Pipe ◽  
Heat Loss ◽  
Heating System ◽  
Hot Water ◽  
Solar Array ◽  
Solar Collectors ◽  
Water Heating ◽  
Evacuated Tube ◽  
Recirculation Loop

This paper describes design, simulation, construction and measured initial performance of a solar water heating system (360 Evacuated Heat-Pipe Collector tubes, 54 m2 gross area, 36 m2 net absorber area) installed at the top of the hot water recirculation loop in the Social Security Mid-Atlantic Center in Philadelphia. Water returning to the hot water storage tank is heated by the solar array when solar energy is available. This new approach, as opposed to the more conventional approach of preheating incoming water, is made possible by the thermal diode effect of heat pipes and low heat loss from evacuated tube solar collectors. The simplicity of this approach and its low installation costs makes the deployment of solar energy in existing commercial buildings more attractive, especially where the roof is far removed from the water heating system, which is often in the basement. Initial observed performance of the system is reported. Hourly simulation estimates annual energy delivery of 111 GJ/year of solar heat and that the annual efficiency (based on the 54 m2 gross area) of the solar collectors is 41%, and that of the entire system including parasitic pump power, heat loss due to freeze protection, and heat loss from connecting piping is 34%. Annual average collector efficiency based on a net aperture area of 36 m2 is 61.5% according to the hourly simulation.

scholarly journals The influence of heat loss from pipes in an unheated basement on the heating energy consumption of an entire typical apartment building

2020 ◽  
Vol 172 ◽  
pp. 12005
Author(s):  
Anti Hamburg ◽  
Targo Kalamees
Keyword(s):  
Energy Balance ◽  
Heat Loss ◽  
District Heating ◽  
Building Energy ◽  
Energy Performance ◽  
Heat Losses ◽  
Hot Water ◽  
Limited Information ◽  
Apartment Building ◽  
Heating Energy Consumption

The majority of old apartment buildings were designed with an unheated basement. Building service systems such as district heating heat exchangers and pipes for domestic hot water and for space heating are usually located in this unheated basement. In addition, these locations are connected with shafts. All these pipe’s heat losses increase air temperature in the basement. If these losses are included into the building energy balance, then they decrease heat loss through the basement ceiling. The basement’s heat balance is also dependent on heat loss from the basement envelope and outdoor air exchange in the basement. In early stages of design, designers and energy auditors need rough models to make decisions in limited information conditions. Once the effects of heat losses from pipes become apparent, they need to be factored into the buildings energy balance, and their effects on heat loss through the basement ceiling needs to be calculated. In this paper we analyse the effect these heat losses have on the service system’s heat gains and heat loss through an uninsulated basement ceiling at different basement insulation levels and with different thicknesses of pipe insulation. From our study we found that pipe losses in the basement increase the building energy performance value by at least 4 kWh/(m²∙a) and their impact on a renovated apartment building is very important.

Study on wellbore heat loss during hot water with multiple fluids injection in offshore well

2016 ◽  
Vol 95 ◽  
pp. 247-263 ◽  
Author(s):  
Wen-Long Cheng ◽  
Bing-Bing Han ◽  
Yong-Le Nian ◽  
Chang-Long Wang
Keyword(s):  
Heat Loss ◽  
Hot Water

Analysis and Research on Natural Circulation Capacity of HFETR

2016 ◽  
Author(s):  
Taozhong Xu ◽  
Caiyu Deng ◽  
Yuxin Xiang
Keyword(s):  
Pressure Vessel ◽  
Cold Water ◽  
Flow Direction ◽  
Natural Circulation ◽  
Reactor Power ◽  
Hot Water ◽  
Forced Circulation ◽  
The Core ◽  
Establishment Process ◽  
Residual Heat

Natural circulation is being used as an important circulation to remove reactor residual heat. In the core of High Flux Engineering Trial Reactor of China (HFETR), the coolant is driven by pumps normally and flows from upside to downside in the core. When HFETR is shut down or runs in low power, the natural circulation between the hot water in the core and the cold water in the reflector inside the pressure vessel is established to cool down the core. Since the natural circulation processed only in the pressure vessel, the accident pumps need to be turned on periodically to remove reactor residual heat. The inversion of flow direction in HFETR and internal natural circulation lead to a different natural circulation establishment process from traditional reactor in which coolant flows form down to top normally. In this paper the transition between the natural circulation and forced circulation is analyzed by RELAP5/MOD3 code. The results showed that the accident pump could be turned off in the power of 850kW; The time, at which the accident pump needs to be turned on to transit the natural circulation to forced circulation, is decided by the temperature of the water in top of pressure vessel, and a formula between temperature of the water in the top of pressure vessel and the reactor power was obtained. The research results have theoretical and practical value to the full use of the natural circulation ability, as well as the safety of the engineering reactors or similar test facilities.

scholarly journals THE ANALYSIS OF WATER SPEED INFLUENCE IN HOT-WATER DISTRIBUTION SYSTEM ON THE AMOUNT OF HEAT LOSS

2021 ◽  
Vol 2021 (1) ◽  
pp. 23-28
Author(s):  
Peter Kapalo ◽  
◽  
Khrystyna Kozak ◽  
Khrystyna Myroniuk ◽  
◽  
...  
Keyword(s):  
Energy Consumption ◽  
Heat Loss ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution System ◽  
Ventilation System ◽  
Hot Water ◽  
Graphical Form ◽  
Hot Water Supply System

One of the main tasks around the world is to reduce energy consumption with constant consumer comfort. The hot water supply system uses a significant part of thermal energy and requires no less attention than the heating or ventilation system. The amount of heat loss from hot water distribution systems is of great importance for the energy consumption of buildings. In winter, part of this heat is used for space heating, in summer they are unused and is considered as lost heat. For this reason, this paper considers the influence of water velocity in the pipe, pipe size, and water temperature on the total heat losses in the insulated hot-water distribution system. The data are presented in tabular and graphical form. A graph of the dependence of the amount of heat loss on the temperature and velocity of hot water is obtained.

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