scholarly journals Impact of Water Temperature Changes on Water Loss Monitoring in Large District Heating Systems

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2060
Author(s):  
Olgierd Niemyjski ◽  
Ryszard Zwierzchowski
Keyword(s):  
Water Temperature ◽  
Water Flow ◽  
Flow Rate ◽  
Water Flow Rate ◽  
District Heating ◽  
Heating System ◽  
Water Volume ◽  
Water Losses ◽  
District Heating System ◽  
Temperature Changes

This paper explores how water temperature changes in a district heating system (DHS) impact the monitoring of water losses. Water volume in DHS is constantly monitored, recorded, and replenished. The leakage and failure status of the DHS is often monitored through measuring the make-up water flow rate. In this paper, we present the methodology and a simplified model of the dynamics of the heating system operation, which was used to determine the profile of changes in the average temperature and density of water in the system. The mathematical model of the district heating network (DHN) was verified by comparing the results of simulation calculations, i.e., calculated values of the temperature of water returning to the heat source, with the measured values. Fluctuations in water temperature cause changes in the density and volume of water in the DHN, which affect the amount of water supplementing the system. This is particularly noticeable in a DHN with a large water volume. The study reports an analysis of measurement results of operating parameters of a major DHS in Poland (city of Szczecin). Hourly measurements were made of supply and return water temperature, water flow rate, and pressure throughout the whole of 2019. The water volume of the analyzed DHN is almost 42,000 m3 and the changes in water volume per hour are as high as 5 m3/h, representing 20–30% of the value of the make-up water flow rate. The analysis showed that systems for monitoring the tightness of the DHS and detecting failures, on the basis of measurements of the make-up water flow rate, should take into account the dynamics of water volume changes in the DHN.

scholarly journals Experimental Investigation on Improvement of Wet Cooling Tower Efficiency with Diverse Packing Compaction Using ANN-PSO Algorithm

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 167
Author(s):  
Hasan Alimoradi ◽  
Madjid Soltani ◽  
Pooriya Shahali ◽  
Farshad Moradi Kashkooli ◽  
Razieh Larizadeh ◽  
...  
Keyword(s):  
Neural Network ◽  
Water Temperature ◽  
Water Flow ◽  
Flow Rate ◽  
Cooling Tower ◽  
Air Flow ◽  
Water Flow Rate ◽  
Pso Algorithm ◽  
Outlet Temperature ◽  
Air Flow Rate

In this study, a numerical and empirical scheme for increasing cooling tower performance is developed by combining the particle swarm optimization (PSO) algorithm with a neural network and considering the packing’s compaction as an effective factor for higher accuracies. An experimental setup is used to analyze the effects of packing compaction on the performance. The neural network is optimized by the PSO algorithm in order to predict the precise temperature difference, efficiency, and outlet temperature, which are functions of air flow rate, water flow rate, inlet water temperature, inlet air temperature, inlet air relative humidity, and packing compaction. The effects of water flow rate, air flow rate, inlet water temperature, and packing compaction on the performance are examined. A new empirical model for the cooling tower performance and efficiency is also developed. Finally, the optimized performance conditions of the cooling tower are obtained by the presented correlations. The results reveal that cooling tower efficiency is increased by increasing the air flow rate, water flow rate, and packing compaction.

Experimental Study on the Desalination System Using Humidification-Dehumidification Technology

2020 ◽  
Vol 1008 ◽  
pp. 177-185
Author(s):  
Hamed Abbady ◽  
Mahmoud Salem Ahmed ◽  
Hamdy Hassan ◽  
A.S.A. Mohamed
Keyword(s):  
Water Temperature ◽  
Water Flow ◽  
Flow Rate ◽  
Water Flow Rate ◽  
Cooling Water ◽  
Operating Conditions ◽  
Outlet Temperature ◽  
Major Objective ◽  
Cooling Water Flow Rate ◽  
Output Ratio

In this paper, an experimental work studies the principal operating parameters of a proposed desalination process using air humidification-dehumidification method. The major objective of this work is to determine the humid air behavior through the desalination system. Different operating conditions including the effect of the water temperature at the entry to the humidifier, the ratio of the mass of water to the air, the air/water flow rate, and cooling water at entry the dehumidifier on the desalination performance were studied. The results show that the freshwater increases with increasing the water temperature at the inlet of the humidifier, the ratio of the mass of water to air, and cooling water flow rate in the dehumidifier. Cooling water outlet temperature at the condenser increases with increasing the water temperature at humidifier inlet. Also, it decreases as increasing cooling water flow rate while the ratio of the mass of water to air achieves the highest productivity and gained output ratio (GOR). The achieved mass ratio (MR) is 4.5 and the mass flow rate of air is 0.8 kg/min.

scholarly journals ANALISIS EKSPERIMEN LAJU ALIRAN VOLUME AIR TERHADAP TEMPERATUR AIR PANAS PADA HEAT RECOVERY SISTEM AC JENIS WATER CHILLER

2011 ◽  
Vol 1 (2) ◽  
Author(s):  
I Made Rasta
Keyword(s):  
Water Temperature ◽  
Water Flow ◽  
Flow Rate ◽  
Heat Recovery ◽  
Tap Water ◽  
Water Flow Rate ◽  
Maximum Heat ◽  
Heating Water ◽  
Compressor Work ◽  
Heat Released

Refrigerant in refrigeration machines will absorb heat from a room space and released the heat to the environment. The heat balancing in the system is heat released from condenser equal with heat absorbed from room space added by the heat equivalent from compressor work. Based on this heat cycle, the writer try to conduct research on using this heat rejection from condenser to heating tap water, focusing on water flow rate increased from 0.5 liter/min to 2.5 liter/min. From experiment and analysis result obtained that the maximum heat water temperature which can be reached is 47.5°C in 0.5 liter/min, with the equipment specifications are 2 HP- split air conditioning and the tank volume is 75 liters. The additional result is heating water temperature is fallen when the water flow rate is increased.

scholarly journals An experimental investigation on the coefficient of performance of the small hot water heat pump using refrigeration R410A and R32

2020 ◽  
Vol 3 (2) ◽  
pp. First
Author(s):  
Le Minh Nhut ◽  
Tran Quang Danh
Keyword(s):  
Ambient Temperature ◽  
Water Temperature ◽  
Water Flow ◽  
Heat Pump ◽  
Flow Rate ◽  
Water Flow Rate ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Electric Heater ◽  
Initial Water

Hot water is an important factor in domestic life and industrial development. Today, the heat pump is used to produce hot water more and more popular because it has many advantages of saving energy compared to the method of producing hot water by the hot water electric heater. The main aim of this study is to evaluate of the coefficient of performance (COP) of the small hot water heat pump using refrigeration R410A and R32. The capacity of both hot water heat pump is similar, one using new refrigerant R32 and other using refrigerant R410A. These heat pumps were designed and installed at the Ho Chi Minh City University of Technology and Education to evaluate the COP for the purpose of application the new refrigerant R32 for hot water heat pump. The compressor capacity is 1 Hp, the volume of hot water storage tank is of 100 liters and is insulated with thickness of 30 mm to reduce the heat loss to invironment, the required hot water temperature at the outlet of condenser is 50 oC, and the amount of required hot water is 75 liters per batch and is controlled by float valve. The experimental results indicate that the COP of the heat pump using the new refrigerant R32 is higher than heat pump using refrigerant R410A from 9% to 15% when the experimental conditions such as ambient temperature, initial water flow rate through the condenser and the required temperature of hot water were the same. In addition, the effect of the ambient temperature, initial water temperature and water flow rate were also evaluated.

A Distributed Predictive Control of Energy Resources in Radiant Floor Buildings

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Soroush Rastegarpour ◽  
Luca Ferrarini ◽  
Foivos Palaiogiannis
Keyword(s):  
Energy Storage ◽  
Model Predictive Control ◽  
Water Flow ◽  
Predictive Control ◽  
Flow Rate ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Water Flow Rate ◽  
Heating System ◽  
Energy Resources

This paper studies the impact of using different types of energy storages integrated with a heat pump for energy efficiency in radiant-floor buildings. In particular, the performance of the building energy resources management system is improved through the application of distributed model predictive control (DMPC) to better anticipate the effects of disturbances and real-time pricing together with following the modular structure of the system under control. To this end, the load side and heating system are decoupled through a three-element mixing valve, which enforces a fixed water flow rate in the building pipelines. Hence, the building temperature control is executed by a linear model predictive control, which in turn is able to exchange the building information with the heating system controller. On the contrary, there is a variable action of the mixing valve, which enforces a variable circulated water flow rate within the tank. In this case, the optimization problem is more complex than in literature due to the variable circulation water flow rate within the tank layers, which gives rise to a nonlinear model. Therefore, an adaptive linear model predictive control is designed for the heating system to deal with the system nonlinearity trough a successive linearization method around the current operating point. A battery is also installed as a further storage, in addition to the thermal energy storage, in order to have the option between the charging and discharging of both storages based on the electricity price tariff and the building and thermal energy storage inertia. A qualitative comparative analysis has been also carried out with a rule-based heuristic logic and a centralized model predictive control (CMPC) algorithm. Finally, the proposed control algorithm has been experimentally validated in a well-equipped smart grid research laboratory belonging to the ERIGrid Research Infrastructure, funded by European Union's Horizon 2020 Research and Innovation Programme.

scholarly journals Active Management of Heat Customers Towards Lower District Heating Return Water Temperature

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1863
Author(s):  
Tommy Rosén ◽  
Louise Ödlund
Keyword(s):  
Energy Efficiency ◽  
Water Temperature ◽  
District Heating ◽  
Heating System ◽  
Active Management ◽  
Electricity Production ◽  
Low Grade ◽  
Efficiency Gains ◽  
District Heating System ◽  
Return Water

The traditional way of managing the supply and return water temperatures in a district heating system (DHS) is by controlling the supply water temperature. The return water temperature then becomes a passive result that reflects the overall energy efficiency of the DHS. A DHS with many poorly functioning district heating centrals will create a high return water temperature, and the energy efficiency of the DHS will be affected negatively in several ways (e.g., lower efficiency of the flue gas condenser, higher heat losses in pipes, and lower electricity production for a DHS with combined heat and power (CHP)). With a strategic introduction of low-grade heat customers, the return water temperature can be lowered and, to some extent, controlled. With the heat customers connected in parallel, which is the traditional setup, return water temperatures can only be lowered at the same rate as the heat customers are improved. The active management of some customers can lower the return water temperatures faster and, in the long run, lead to better controlled return water temperatures. Active management is defined here as an adjustment of a domestic heating system in order to improve DHS efficiency without affecting the heating service for the individual building. The opposite can be described as passive management, where heat customers are connected to the DHS in a standardized manner, without taking the overall DHS efficiency into consideration. The case study in this article shows possible efficiency gains for the examined DHS at around 7%. Looking at fuel use, there is a large reduction for oil, with 10–30% reduction depending on the case in question, while the reduction is shown to be largest for the case with the lowest return water temperature. The results also show that efficiency gains will increase electricity production by about 1–3%, and that greenhouse gas (GHG) emissions are reduced by 4–20%.

scholarly journals Testing Novel New Drip Emitter with Variable Diameters for a Variable Rate Drip Irrigation

Agriculture ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 87
Author(s):  
Hadi A. AL-agele ◽  
Lloyd Nackley ◽  
Chad Higgins
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Drip Irrigation ◽  
Water Flow Rate ◽  
Data Repository ◽  
Operating Pressure ◽  
Variable Rate ◽  
Water Losses ◽  
Full Field ◽  
Outside Diameter

This research presents a new variable rate drip irrigation (VRDI) emitter design that can monitor individual water drops. Conventional drip systems cannot monitor the individual water flow rate per emitter. Application uniformity for conventional drip emitters can be decreased by clogged emitters, irregular emitter orifices, and decreases in pressure. A VRDI emitter can overcome the irrigation challenges in the field by increasing water application uniformity for each plant and reducing water losses. Flow rate is affected by the diameter of the delivery pipe and the pressure of the irrigation delivery system. This study compares the volumetric water flow rate for conventional drip emitters and new VRDI emitters with variable diameters inner (1 mm, 1.2 mm, 1.4 mm, and 1.6 mm) and outside (3 mm, 3.5 mm, 4 mm, and 4.5 mm) with three pressures (34 kPa, 69 kPa, and 103 kPa). The tests revealed that the new VRDI emitter had flow rates that increased as the operating pressure increased similar to a conventional drip tube. The flow rate was slightly increased in the VRDI with pressure, but even this increase did not show large changes in the flow rate. The flow rate of the conventional drip tube was 88% larger than the VRDI emitter for all pressures (p < 0.05). However, operating pressure did not affect the drop sizes at the VRDI emitter, but the generalized linear mixed models (GLM) results show that volume per drop was impacted by the outside diameter of the VRDI outlet (p < 0.05). The interaction between the inner and outside diameter was also significant at p < 0.01, and the interaction between outside diameter and pressure was statistically significant at p < 0.01. The electronic components used to control our VRDI emitter are readily compatible with off-the-shelf data telemetry solutions; thus, each emitter could be controlled remotely and relay data to a centralized data repository or decision-maker, and a plurality of these emitters could be used to enable full-field scale VRDI.

scholarly journals The community heating network’s thermal condition assessment

2021 ◽  
pp. 136-142
Author(s):  
Alexander Aleksakhin ◽  
Iryna Dubynskaya ◽  
Ilona Solyanyk ◽  
Zhanna Dombrovs’ka
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Water Flow Rate ◽  
Heating System ◽  
Ambient Air ◽  
Heat Losses ◽  
Main Direction ◽  
Heating Period ◽  
Uniform Diameter ◽  
System Water

Heat losses at the heating network’s distribution pipelines were identified for Karkivcommunity. Heat losses’ calculation is performed in view of the underground pipelines’ installationin non-accessible ducts. The heating system water temperature is accepted in line with the heatingnetwork temperature chart and according to the design outdoor temperature value for heatingpurposes. Specific heat losses in the network section’ pipelines are accepted at the level of standardvalues for the specified network laying method. The water flow rate at the heat pipeline sections isdefined as per the design heat loads from the buildings connected to the heat supply network. Theheat pipeline segment with uniform diameter is accepted as the rated section. The soil temperatureat the heat pipeline axis laying depth is accepted as 5°C. The heat losses at the structural networkelements are considered by 1.15 coefficient. The calculations are performed in view of the heatingsystem water flow rate and temperate changes along the heat pipeline length. While analyzing thethermal condition of the return pipelines of the community heating network, the changes in the heatcontent of the heating system water flow in the main direction pipeline during mixing with the waterflow from the branches of the main direction line are taken into account. Considering the averagetemperature of the coldest five days consecutively, the total energy loss in heating pipeline for a groupof buildings in Kharkov region are equivalent to 180.8kW.In view of the ambient air temperature changing over the heating period for Kharkiv cityclimate conditions and the current schedule for quality heat energy supply to the consumers controlthe annual heat losses in the community heating network pipelines were calculated. The soil temperature change at the heat pipeline installation depth during the heating period was notconsidered.Heat losses in the microdistrict network for the year are 2184 GJ. The data obtained can beused to compare options when developing a strategy for reforming the microdistrict heat supplysystem.

scholarly journals To Combine or Not To Combine An In-Depth Review of Standard and Combined Hydronic Systems and Their Various Pitfalls

1993 ◽  
Vol 10 (2) ◽  
Author(s):  
Edward W. Saltzberg
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Water Flow Rate ◽  
Heating System ◽  
Hot Water ◽  
Space Heating ◽  
System Pressure ◽  
Hot Water Supply ◽  
Heating Boiler

A hydronic heating system is simply a piping arrangement conveying hot water to heat exchangers in order to provide space heating. A conventional hydronic heating system usually delivers hot supply water at 180 to 200 Fahrenheit temperature and has a dedicated space heating boiler. The hot water return temperature is usually about 140 Fahrenheit, meaning a 40 to 60 temperature difference between supply and return. The conventional hydronic heating system has a relatively constant circulated water flow rate and the temperature of the delivered hot water supply can be reset from outside air temperature. The water flow balancing of a conventional hydronic heating system is somewhat straightforward, although quite critical. The pipe sizing is determined on the basis of gallons per minute flow rate, the selected system pressure drop, and the maximum prudent velocity for the specific piping material. The circulating pump is selected on the basis of the required gallons per minute

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