A Methodology of Selection Domestic Hot Water flow Counters for Multifamily Buildings

A Methodology of Selection Domestic Hot Water flow Counters for Multifamily Buildings Procedia Engineering 165 ( 2016 ) 1281 – 1286 Available online at www sciencedirect com 1877 7058 © 2016 The Autho[.]

Procedia Engineering 165 ( 2016 ) 1281 – 1286

1877-7058 © 2016 The Authors Published by Elsevier Ltd This is an open access article under the CC BY-NC-ND license

( http://creativecommons.org/licenses/by-nc-nd/4.0/ ).

Peer-review under responsibility of the scientific committee of the 15th International scientific conference “Underground Urbanisation as a

Prerequisite for Sustainable Development

doi: 10.1016/j.proeng.2016.11.851

ScienceDirect

15th International scientific conference “Underground Urbanisation as a Prerequisite for

Sustainable Development”

A methodology of selection domestic hot water flow counters

for multifamily buildings

Viktor Pukhkal a,*, Aleksandr Yeremkin b, Aleksandr Tsygankov c, Boris Moiseev d a

St Petersburg State University of Architecture and Civil Engineering, 2-ya Krasnoarmejskaja str 4, St Petersburg, 190005, Russia

b

Penza State University of Architecture and Construction,German Titov str 28, Penza, 440028, Russia

c

St Petersburg National Research University of Information Technologies, Mechanics and Optics, Lomonosov str 9, St Petersburg, 191002,

Russia

d

Tyumen industrial University, Volodarskogo str 38, Tyumen, 625000, Russia

Abstract

"Design regime for current water consumption" is proposed to use when performing calculations of water consumption in hot water supply systems in multi-family buildings Design regime is a simplified mathematical description of all ordered sets of time costs expected in the current period of hot water system operation The design regime of water consumption is described by the ratio of total hourly irregularity at 98% supply (security) When choosing a water flow counter in the hot water supply of multifamily buildings value of the operational water flow counter must comply with the parameters of water consumption of the building to the greatest extent The methodology is proposed and an example of calculation of the amount of water per day passing through the water flow counter when water flow is below threshold values, the smallest and the transitional costs for the flow counter is made

© 2016 The Authors Published by Elsevier Ltd

Peer-review under responsibility of the scientific committee of the 15th International scientific conference “Underground Urbanisation as a Prerequisite for Sustainable Development

Keywords: multifamily buildings, hot water supply, a selection of domestic hot water flow counter;Introduction

1 Introduction

Water metering units with the hot water counters installation are provided for measuring the water consumption on

* Corresponding author

E-mail address: pva1111@rambler.ru

© 2016 The Authors Published by Elsevier Ltd This is an open access article under the CC BY-NC-ND license

( http://creativecommons.org/licenses/by-nc-nd/4.0/ ).

Peer-review under responsibility of the scientific committee of the 15th International scientific conference “Underground Urbanisation as a Prerequisite for Sustainable Development

hot water supply inputs in multifamily buildings Pre-selection of the nominal diameter of tachometer water counter

isproduced by the estimated daily water consumption for hot water [1] (tab.1)

The principal characteristics of tachometer water counters are:

x instrument threshold m

h

Q - the flow rate at which the rotary-disk or turbine of water counter start continuous rotation (the consumption below the threshold is not recorded by the water counter);

x minimum consumptionQminm is the consumption at which the water counter has a relative error of ±5% and below which the relative error is not metered;

x transitional consumption m

t

Q is consumption at which the water counter has an error of ±2%, and below which an error is of ±5%;

x nominal consumption m

nom

Q is consumption (equal to 1/2 maximum consumption) at which the counter can operate continuously for long time;

x maximum consumption m

Qmax is the consumption at which the counter may not work more than for 1 hour per day;

x operational consumption m

e

Q is the consumption at which the counter can run continuously for a lifetime

Table 1 Choice of water flow meter nominal (inside) diameter

Estimated dayly water comsumption, m 3 per

day

Nominal (inside) diameter, mm , for water flow counters

rotary-disk water counters turbine water counters

The water counter is checked for measurement capabilities for the minimum hot water consumption per hour; the minimum water consumption for the selected counter must not exceed the estimated minimum of water consumption per hour

The instantaneous consumption at any point of the hot water system is a random variable Water consumption

chart for hot water supply on hours of the day is always uneven for all consumers [4-15] Water consumptions vary

from zero values (lack water draw-off; for example, at night) to maximum ones; in some cases it is impossible to determine the minimum water consumption per hour

The unaccounted amount of water during the reporting period that has passed through the water counter at a

consumption below the threshold of the water counter, or exceeding fiducial value of ±2%, - at a consumption

below the transition for the water counter, cannot be determined in any way and causes distrust of the measurement results

2 Research approaches

Quantity estimation of consumed hot water is based on the results of quantitative consumption measurement Water counters nominal diameter should be selected by comparison of their technical and metrological parameters with the expected water consumption at on-site measuring The main criterion that should be considered when selecting water counters (water meters), is the range of consumptions to be fixed

The operational consumption value of the water counter should correspond to the greatest extent to the parameters of water consumption of the building This is possible if the valueQe m is equal to the average hourly water consumption in the system during the consumption periodQhm, and the relation between different parameters

of water counters will coincide with consumption regimes such as minimumKmin and maximumKmaxcoefficients

of hourly irregularity factor, i.e

m e Q

m t Q hm Q

Q

m e Q m

hm Q

Q

K max max

Currently, there is an approach to determine the estimated coefficient of hourly water consumption irregularity

h

K [11,12], corresponding toKmax

hm Q

h

Q

h

K max

(3)

where Qhmax - is the maximum hourly hot water consumption, m3 per hour; Qhm - is the average hourly hot water consumption, m3 per hour

Maximum water consumption corresponds to a particular supply in relation to the period of maximum water consumption, taken conditionally (within one or more hours) All consumptions outside this conditional maximum, regardless of their rate are not to be considered Guidelines for the calculation Kmindo not exist

The paper [4] presents “estimated water consumption mode”, which is a simplified mathematical description of the entire ordered set of hourly consumptions expected in the estimated operation period of the hot water system It

is offered to select hot water counters in в multifamily buildings

Hourly hot water consumptions are described by dependence

1



˜

˜

6 Q hm K T K

where T is the time in fractions of the total period of water consumption;

K - the ratio of hourly irregularity of water consumption

The ratio of total hourly irregularity of X% supply

hm Q hX Q X K

where KX% is the ratio of the total hourly irregularity of X% supply;

%

hX

Q is hourly water consumption of X% supply;

hm

Q is the average hourly water consumption in the supply system

The term “general hourly irregularity” indicates that values QhX% and Qhm refer to the whole considered period

of water consumption (e.g., a year)

The water consumption volume for the time during which the flow rate of water passing through the water counter does not exceed the set value Qmin(equal to, for exampleQt m, or Qminm ),

1 min min



¹

·

¨

©

K

K

K

where Q6min is the water consumption value in relative units within the time period Tmin

3 Methodology and sample of selection of water flow counters

The methodology of calculating the water amount passed through the counter for hot water needs per day when сonsumption is below the transition consumption value for the counter:

x the characteristics of the estimated chart for hot water consumption are set up by the norms [1]: average daily consumption and the hourly irregularity ratioK;

x the likely average consumption of hot water per every hour per day are determined by the dependence (6) and the consumption value in physical terms (l/h, m3/h) are calculated;

x analysis of the calculation results is carried out and the values of hourly consumption beyond the range of

consumption recorded by the heat meter are set up

Here is an example of use of the proved dependences for the estimation of measurement uncertainty for the consumed hot water amount

Initial data:

x multifamily building with a centralized hot water supply system, equipped with bathtubs 1700 mm long with showers; the number of inhabitants of the multifamily building is 265 people;

x the maximum hourly hot water consumption is Qh.max= 4.302 m3/h;

x the average hourly hot water consumption is Qh.m= 0.985 m3/h;

to determine the amount of water, water counter ВСГ Dу20 produced by JSC "Teplovodomer" (Mytishchi) with the following characteristics is used:

x threshold is m

h

Q = 0.02 m3/h;

x minimum water consumption is m

Qmin= 0.1 m3/h;

x transitional water consumption is m

t

Q = 0.25 m3/h;

x operational water consumption is m

e

Q = 1.5 m3/h;

x nominal water consumption is Qm = 2.5 m3/h;

x maximum water consumption is m

Qmax= 5 m3/h

the ratio of total hourly irregularity of 98% supply [4] is determined by the research results K K98%=3.58

For the selected water counter Qh.m= 0.985 м3/ч < m

e

Q = 1.5 m3/h; Qh.max= 4.302 м3/ч < m

Qmax= 5 m3/h

The water consumption volume in relative units for the time during which the water flow rate through the water counter does not exceed values:

water counter threshold Qh m

0203 0 985 0

02 0

min

m h Q

m h Q

; 00076 0 1 58 3

58 3

58 3

0203

¹

·

¨

©

§

m h Q Q

minimum water consumption Qminm

1015 0 985 0

1 0

min min

m h Q

m Q

; 0071 0 1 58 3 58 3

58 3

1015 0 min



¹

·

¨

©

§

m Q Q

transitional water consumption Qt m

2538 0 985 0

25 0

min

m h Q

m t Q

0254 0 1 58 3

58 3

58 3

2538

¹

·

¨

©

§

m t Q Q

4 Conclusion

The selected water counter:

x does not account water consumption below the threshold in the amount of 0.076% of the total volume of water consumption;

x accounts water consumption with a relative error of ±5% in the amount of 0.71% of the total volume of water consumption;

x accounts water consumption with a relative error of more than ±2% in the amount of 2.54% of the total volume of water consumption

Insights

The selection of counters is based on consumption to be measured When selecting water counters caliber (diameter) comparison of their technical and metrological parameters with the expected on-site measurements of water consumption must be made

"The design mode of consumption" should be used to estimate the amount of water passing through the water counter at consumption below the value of the minimum or transitional consumption

"The design mode of consumption" is a mathematical description of the entire ordered set of hourly consumptions expected in the estimated period of hot water system operation

The laws of probability theory and accumulated statistical data – daily water consumption charts by different consumers should be used for calculating the estimated mode of water consumption

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