Hot Water Pipes Research Articles

자연순환형 태양열온수기 동파방지기술

In the present work, a new freeze protection method has been proposed for a natural circulation system of solar water heater. Though electrothermal wire is popularly used for the purpose, there are freezing troubles by wire cut-off and shortage of excessive electric power consumption. In the experimental device, hot water in storage tank was used to heat the outlet pipe from the tank if the pipe surface temperature falls lower than a set point. The cold water pipe to the storage tank was installed to directly contact the hot water pipe surface temperature rose by transferred heat.

H214 分散蓄熱技術を応用した集合住宅用コージェネレーションシステム : 太陽熱との組合せシステムの検証(OS4 省エネルギー・コジェネヒートポンプ)

In order to spread economically viable distributed generation systems for apartment buildings, it is essential to develop an efficient and low-cost heat supply system. We are developing a new cogeneration system (Neighboring Co-Generation system: NCG). The key concept of this system is to install a heat storage unit with a hot water supply and a room heating function at each household and to connect heat storage units by a single-loop hot water pipe. In this study, a dynamic simulator was developed on the NCG system with solar heat utilization, and the environmental load reduction effects of solar heat utilization in the system were evaluated under the condition satisfying the whole heat demand. The simulated results for the system of 50 households showed that the annual use of the primary energy was reduced by 18% in the case that a gas engine was used as the main generator. When a SOFC system with the higher thermal efficiency was installed, the reduction ratio increased to 29%.

Removal of Calcium Ions from Aqueous Solution by Phosphosilicate Glass

Water containing calcium ions often leads to scaling problems in hot-water pipes, heaters, and boilers. The building up of this scale deposit is a common and costly problem in many industrial processes. Recently, glasses with a special composition have shown the ability to remove some hazardous ions from waste solutions. In the present study, a 45SiO2–4P2O5–16B2O3–20Na2O–15K2O glass system was used to remove calcium ions from an aqueous solution. When this phosphosilicate glass was reacted in a solution containing calcium ions, the calcium ions were eliminated by forming calcium phosphate crystals on the glass surface. For this calcium removal process to occur, phosphorus ions must be supplied from the glass through ion leaching. Reaction under a dynamic condition and an increased surface area of the glass enhanced the removal rate of calcium ions from the solution. The calcium ion removal efficiency was also increased by the crystallization of the glass.

A Study of an Earthworm Type Inspection Robot Movable in Long Pipes

This paper describes development of a three somites earthworm type mobile inspection robot which is able to move in long pipes. We have many small diameter pipes which are gas or water pipes for individual or corporate houses and boilers or hot water pipes for industries. They are settled in the ground horizontally or in the narrow spaces vertically and some of them are covered by casings or hard heat insulating matters. It is very difficult to inspect from out of the pipes. If we can insert a mobile inspection robot into the pipes from the suitable position, we are easy to inspect the pipes. Authors fabricated a three somites earthworm type mobile inspection robot in which we use three rubber bellows as pneumatic actuators. Sixteen rubber friction rings are used to get friction force between pneumatic actuators and the pipes. The electromagnetic valves and air-feeding tubes for the pneumatic actuators are carried on trolleys in order to decrease friction force between the pipes and them. The fabricated three somites earthworm type mobile inspection robot can move in a pipe which is 78 mm in inner diameter and vertical pipe carrying a load that is equivalent to the air-feeding tube of 32 m length. Consequently, the inspection robot was confirmed to move in the long pipes.

分散蓄熱を利用した集合住宅用コージェネレーションシステムの熱供給特性および環境負荷低減効果(熱工学,内燃機関,動力など)

In order to spread economically viable distributed generation systems for apartment buildings, it is essential to develop an efficient and low-cost heat supply system. We are developing a new cogeneration system (Neighboring CoGeneration system: NCG system). The key concept of this system is to install a heat storage unit in each house for hot water supply and room heating and to connect heat storage units by a single-loop hot water pipe. The system leads to time leveling of the total heat supply and reduction of installation cost. Furthermore, it is expected that the cogeneration can operate according to electricity demand because of the large heat capacity of accumulation of the system. In this study, a dynamic simulation model was developed to evaluate the performance of the heat supply system and the environmental load-reduction effect of the NCG system for 50 households. It showed that the NCG system can supply enough heat for peak demand in winter and decrease 23% in CO_2 emission on yearly average.

B106 分散蓄熱技術を応用した集合住宅用コージェネレーションシステムの省エネ性評価(OS3 省エネルギー・コジェネ技術),動力エネルギーシステム部門20周年,次の20年への新展開)

In order for economically viable distributed generation systems for apartment buildings to spread, it is essential to develop an efficient and low-cost heat supply system. We are developing a new cogeneration system (Neighboring CoGeneration: NCG). The key concept of this system is to install a heat supply unit with a hot water supply and a room heating function at each household and to connect different households by a single-loop hot water pipe. As a result, time leveling of the heat supply and heat transferring among households become possible. Thus, the costs of the piping and the heat source equipment decrease. Furthermore, because all the heat supply units store heat, the total heat storage capacity is large enough for cogeneration to generate according to the electricity demand and with high operating rate. In this paper, we reported the evaluation of the performance of the heat supply and the energy saving effect of NCG system for 50 households in winter by the dynamic simulation.

Thermal property improvement of ethylene‐octene copolymer through the combined introduction of filler and silane crosslink

AbstractIn many applications, e.g., wire and cable insulation, hot water pipe, high‐temperature properties of polymer are essential. This article presents the use of silane crosslinking together with the addition of particular filler in improving the thermal and mechanical properties of ethylene‐octene copolymer (EOC). The effects of filler surface characteristics on siloxane network structure developed and final properties of the crosslinked products are discussed. The results show an increase in the decomposition temperature of EOC more than 50°C after modification. Only crosslinked composites are able to withstand the high‐temperature environment of aging test which is beyond the melting temperature of the matrix polymer. The crosslinked composites filled with calcium carbonate show superior properties to those with silica, due to a higher crosslink density and tighter network structure formed. The silane coupling mechanism and the presence of bound polymer on silica surfaces cause difficulties for the crosslink formation in the silica filled systems. However, an advantageous influence of both silane coupling and crosslink reaction in the silica filled composites is seen on the enhanced tensile strength and modulus of the materials. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

E109 A Cogeneration System for an Apartment Building Based on Distributed Heat Storage Technology(Distributed Energy System-2)

In order for economically viable distributed generation systems for apartment buildings to spread, it is essential to develop an efficient and low-cost heat supply system. We have developed a new cogeneration system called the Neighboring Cogeneration system (NCG). The key concept of this system is to install a heat accumulator with a hot water supply and a room heating function at each household and to connect different households by a single loop of hot water pipe. As a result, time leveling of the heat supply and heat transferring among households becomes possible. Thus, the costs of the pipe and the heat source equipment decrease. Furthermore, because all of the heat accumulators store heat, the total heat storage capacity is large enough for cogeneration to generate exhaust heat according to the electricity demand and with a high operating rate. In this paper, we report the results of the NCG system for 7 lived-in households. The controlling system worked efficiently. All of the households were able to use hot water without any difficulties. Further, we report the results of the energy saving effect of the NCG system for 50 lived-in households by means of a simulation based on the experimental results for NEXT21.

C213 集合住宅用セントラル熱供給システムに関する研究(OS4 省エネルギー・小型分散電源・コジェネ技術)

In order for economically viable distributed generation systems for local community to spread, it is essential to develop an efficient and low-cost heat supply system. For this purpose, we are proposing a new heat supply system. The key technology for the system is to connect compact heat supply units with hot water heat storage tank installed in each house by a single loop hot water piping. It is expected that flow rate of hot water supply can be reduced by using distributed heat storage. The effect leads to reduction in pipe diameter, heat loss and pump power. In this study, to confirm the effect on leveling heat transfer rate through the main pipe, a dynamic simulator for heat supply system to 50 households was developed, and the effect of operation mode and capacity of distributed heat storage was evaluated.

The Impact of Overhead Heating System Height on Greenhouse Air Temperature, Air Movement, and Canopy Temperature

The effects of a movable heating system on distribution and uniformity of air temperature, air movement, and canopy temperature were studied in a greenhouse. A movable heating system consisting of hot-water pipes was placed over the top of the plant canopy at six different heights (0.25, 0.5, 0.75, 1.0, 1.25, and 1.45 m) and compared with a fixed overhead heating system placed 1.6 m above the top of the plant canopy. The movable heating system influenced the distribution and uniformity of the air temperature in the greenhouse. The change in temperature distribution was closely related to the position of the heating pipes. The movable heating system increased the air velocity near the plant canopy when placed at the two lowest positions, but at higher positions air velocity was similar to that measured for the fixed overhead heating system. The leaf temperature was correlated with air temperature but was not influenced by the position of the movable heating pipes.

Infants under 1 year of age have a significant risk of burn injury

A wealth of data exists concerning paediatric burn epidemiology in general, but very little exists specifically in infants under 1 year of age, a special group in which mobility begins to develop. A retrospective study of all burn admissions of infants under 1 year old to The Welsh Centre for Burns from January 2003 to January 2006 was performed. During the 3-year period there were 104 new burns cases identified which represents 11.8% of all paediatric admissions. 63.5% (66) were treated as inpatients and 36.5% (38) treated as out-patients. Burns increased in frequency with increasing age and occurred mainly in the home. Scalds were the commonest type of burn in 65% (68) whilst the second most common was contact burns which accounted for 30% (31). The most common source of scald was from cups containing hot drinks (39%) and the most common source of contact burn was radiators/hot water pipes (30%). The mean TBSA was 2.3%, (range 0.5–38%). The frequency of burns in the under 1 year old population highlights a need for emphasis of burn prevention directed to this group. Special attention is needed to look at the specific aetiology of these burns. Starting points for prevention should address the number of burns surrounding hot drinks and bottle warming practices in the case of scalds and the dangers of household radiators and hot water pipes in the case of contact burns.

A New Heat Supply System of Cogeneration for the Local Community

In order for economically viable distributed generation systems for local communities to be widely accepted, it is essential to develop an efficient and low-cost heat supply system. For this purpose, we propose a new heat supply system which we already presented at the ICOPE-05 Chicago. The key technology for the system is to connect compact heat supply units with a heat storage function installed in all the households of the local community, such as condominiums, by a single-loop of hot water pipe. A phase change material was used for the heat supply unit as the heat storage material. However, for easier handling and reducing the cost of the unit, we have developed a new heat supply unit whose heat storage tank is made of plastic. Hot water for space heating is used as the heat storage material. Further we constructed a heat supply system for 7 lived-in households with a 5 kW gas engine and a 42 kW boiler as the heat sources.Some experiments with a heat supply unit and a heat supply system, such as for heat storage and heat supply for peak demand were conducted. Additionally, dynamic simulations of heat demand by 50 households and a COP evaluation of a new CO2 heat pump system using low-temperature exhaust gas from the gas engine were also conducted.

FABRICATION OF AN IN-PIPE MOBILE INSPECTION ROBOT DRIVEN BY PNEUMATIC PRESSURE AND IMITATING MOVING OF A GREEN CATERPILLAR

We have many small diameter pipes that are gas or water pipes for individual or corporate houses and boilers or hot water pipes for industries. They must be periodically inspected in order to protect the accident previously. Diameters of these pipes are different at the place where pipes change from the main to the branch and a step comes here. The inspection robot for these pipes must move different diameter and go over the step. We propose a mobile robot that imitates the moving of a green caterpillar. The robot is constructed by the eight parallel rubber bellows and three suction brakes. The fabricated mobile robot was confirmed to move in different diameter pipes whose diameters are more than 70 mm. Its speed was 20 mm/s.

Influence of hydraulic tests and the temperature of hot water on the properties of pipe metal

712 The state of metal in hot-water pipes depends on many factors, including the working stress, the temperature and chemical composition of the water, and the cyclic (static and dynamic) loads associated with hydraulic tests and with external vibrations [1]. Standard tests of the mechanical properties—the strength, the plasticity, and even the impact strength—do not permit estimation of the change in metal characteristics and its degradation in the course of operation [2, 3]. Currently, many methods permit the detection of changes in the pipe metal and prediction of pipe behavior and life [3, 4]. Besides the working pressure of 0.6‐1 MPa, pipes in major pipelines are periodically subjected to hydraulic tests at 2.6 MPa. The high stress arising in the pipe wall during such tests, together with the temperature of the hot water, will impair the strength of the metal. The magnitude of this effect must be determined in selecting the optimal pressure of the hydraulic tests and the chemical composition of the steel. In the present work, we propose methods of simulating the influence of periodic hydraulic tests and the water temperature on the mechanical properties and strength of the metal determined in tensile tests of smooth samples and flexure of notched samples. To study the influence of hydraulic tests on the state of the metal, we select fragments (surface area up to 5 m 2 ) of steel 20 and 171 Ee steel pipe from the emergency reserve, from current production, and after 20 years of operation. Table 1 presents the chemical composition of the pipe. The resistance to crack nucleation and propagation is determined on samples with a sharp notch (of type 13 according to State Standard GOST 9454-78) in point flexure on an Instron machine (crosspiece speed 0.2 cm/min); the load‐strain diagram is recorded. From the test data, we calculate the flexure strength σ d , the overall yield point in the notch σ oy , the plasticity (the distance of plastic flexure) f pl , the work of failure A Σ , and its components A n (the work of crack nucleation) and A p (the work of crack propagation).

Insulation plan of aluminum curtain wall-fastening unit for high-rise residential complex

Aluminum curtain wall system is commonly used in high-rise residential complex. For the energy-efficient curtain wall system, the insulation performance of the fastening unit, which enjoins the curtain wall unit to the slab, should be improved because in Korea, hot water pipes for radiant heating are typically installed on the slab in residential buildings. However, this fastening unit composed of metals with high thermal conductivity, acts as a thermal bridge that increases heat loss. Therefore, in this study, we aim to develop a more effective insulation method for the fastening unit. Three alternative fasteners coated with urethane foam and insulation paint were selected (Case 1: using the existing fastener; Case 2: coating the upper part of fastener with urethane foam; Case 3: coating the entire surface of fastener with insulation paint; Case 4: coating the upper part of fastener with urethane foam and the lower part with insulation paint). The heat loss and economical efficiency of each case were analyzed through the three-dimensional annual transient heat transfer simulation and payback period method, respectively. Case 4, compared to Case 1, was found to show the best performance of reducing the annual heat loss by 8.14%. From an economical efficiency perspective, however, Case 2 was found to have the shortest payback period of 2.27years.

Preparation of Silane-Grafted and Moisture Crosslinked Low Density Polyethylene. Part II: Electrical, Thermal and Mechanical Properties

Among different polyethylene cross-linking methods, such as peroxide, irradiation, and silane cross-linking, silane-based methods are the most suitable methods for producing cable insulation and hot water pipe materials due to process simplicity and superior properties of its product. Some electrical, thermal and mechanical properties of silane-grafted water-cross-linked polyethylene were investigated. The effects of silane grafting and gel content on volume resistivity, tensile properties and melting behavior of low density polyethylene (LDPE) were studied. Results indicated that volume resistivity increased with increasing gel content. Stress at break increased with increasing grafting level and gel content. Elongation at break increased with grafting and decreased with gel content. High temperature tensile properties showed that cross-linked polyethylene (XLPE) is more stable than LDPE at high temperature. In differential scanning calorimetry (DSC) analysis a broad endothermic peak appeared for XLPE due to phase separation. Melting point and crystalline percentage decreased with increased grafting level and gel content. Incorporation of carbon black into XLPE reduced the volume resistivity and degree of crystallization.

0S9-9 熱連系を考慮した民生用コージェネレーションのダイナミックシミュレーション(OS9 熱流動,循環型社会における動力エネルギー技術)

In order for economically viable distributed generation systems for local community to spread, it is essential to develop an efficient and low-cost heat supply system. We have proposed a new heat supply system presented at ICOPE-03 Kobe and ICOPE-05 Chicago. The key technology for the system is to connect compact heat supply units installed in all the households of the local community, such as a condominium, by a single loop of hot water piping. Phase change material such as paraffin was used for a heat supply unit as heat storage material. However we have developed a new heat supply unit made of plastic water tank for ease to use and a serious cost reduction. Hot water for space heating is used as heat storage material. Some experiments for a heat supply unit and dynamic simulations for heat demand have been conducted, such as heat storage and supply of the heat supply unit, and COP evaluation of a new CO_2 heat pump system using low- temperature exhaust gas. In this paper, experimental results on the performance of the new heat supply system installed to 7 households in condominium, and evaluation of dynamic simulation for 50 households using 1B hot water piping are presented.

Increasing solar gains by using hot water to heat dishwashers and washing machines

Seventy to ninety percent of the electric energy used by dishwashers and washing machines heats the water, the crockery, the laundry and the machine and could just as well be replaced by heating energy from solar collectors, district heating or a boiler. A dishwasher and a washing machine equipped with a heat exchanger and heated by a hot water circulation circuit instead of electricity (heat-fed machines) have been simulated together with solar heating systems for single-family houses in two different climates (Stockholm, Sweden and Miami, USA). The simulations show that a major part of the increased heat load due to heat-fed machines can be covered by solar heat both in hot and cold climates if the collector area is compensated for the larger heat load to give the same marginal contribution. Using ordinary machines connected to the hot water pipe (hot water-fed machines) and using only cold water for the rinses in the washing machine gives almost the same solar contribution; however considerably lower electrical energy savings are achieved. The simulations also indicate that improvements in the system design of a combisystem (increased stratification in the store) are more advantageous if heat-fed machines are connected to the store. Thus, using heat-fed machines also encourages the use of more advanced solar combisystems.

Dishwasher and washing machine heated by a hot water circulation loop

Electric energy (70–90%) used by electrically heated dishwashers and washing machines is used for heating the water, the crockery, the laundry and the machine and could as well be replaced by heat from other sources than electricity. This article evaluates prototypes of a dishwasher and a washing machine, where the machines are heated by a hot water circulation loop and the heat is transferred to the machines via a heat exchanger. The machine therefore uses water from the cold water pipe. Measurements and simulations have been performed showing that all energy for heating can be replaced if the supply water temperature is 65–70 °C. An alternative and common way to save electricity is to connect the machines to the domestic hot water pipe, but the electrical savings with this measure are much smaller, especially for the dishwasher. Computer modelling has been performed and the model has proved to have a high agreement with measured data. However comparison with manufacturers’ data indicates that the computer models overestimate the energy demand by about 10%.

The Mpemba effect: When can hot water freeze faster than cold?

We review the Mpemba effect, where initially hot water freezes faster than initially cold water. Although the effect might appear impossible, it has been observed in numerous experiments and was discussed by Aristotle, Francis Bacon, Roger Bacon, and Descartes. It has a rich and fascinating history, including the story of the secondary school student, Erasto Mpemba, who reintroduced the effect to the twentieth century scientific community. The phenomenon is simple to describe and illustrates numerous important issues about the scientific method: the role of skepticism in scientific inquiry, the influence of theory on experiment and observation, the need for precision in the statement of a scientific hypothesis, and the nature of falsifiability. Proposed theoretical mechanisms for the Mpemba effect and the results of contemporary experiments on the phenomenon are surveyed. The observation that hot water pipes are more likely to burst than cold water pipes is also discussed.