Energy Use and Performance of a New Variable Primary-Flow Chilled Water System

Solar Energy ◽  
2005 ◽  
Author(s):  
Li Song ◽  
Ik-Seong Joo ◽  
Mingsheng Liu
Keyword(s):  
Pump Power ◽  
Water Supply ◽  
Water Flow ◽  
Water System ◽  
Variable Flow ◽  
Chilled Water ◽  
Flow Through ◽  
Compressor Power ◽  
Cooling Coil

The traditional chilled water loop has been designed as a primary/secondary (P/S) system for several years. The primary loop maintains constant chilled water flow through the evaporator, and the secondary loop is designed as a variable flow system in response to variations in building cooling load. The primary/secondary design separates the chiller operation from the building load requirements. This design principle has been working adequately for old chillers that require constant chilled water flow to achieve stable chiller performance. However, these chillers operate inefficiently and consume unnecessary pump power. In recent years, the chiller industry has begun the use of variable water flow through evaporators. Significant energy savings can be achieved by using the variable flow principle. This paper compares the P/S system with variable chilled water system and also proposes an innovative solution: chilled water supply temperature reset to maintain the minimum chilled water flow and eliminate by-pass water flow. The energy consumption models including pump power and chiller compressor power improvement are presented to simulate the energy performance of two systems. ASHRAE detailed cooling coil models are also adopted to simulate the cooling coil discharge air humidity in order to verify the impacts of the chilled water supply temperature reset. Finally, a case study building demonstrates experimental results. Up to 10% pump and compressor power saving is demonstrated by simulations and the case study.

scholarly journals Contamination of hospital linen by Bacillus cereus

1994 ◽  
Vol 113 (2) ◽  
pp. 297-306 ◽  
Author(s):  
D. Barrie ◽  
P. N. Hoffman ◽  
J. A. Wilson ◽  
J. M. Kramer
Keyword(s):  
Water Supply ◽  
Bacillus Cereus ◽  
Water Flow ◽  
Washing Machine ◽  
Chemical Additives ◽  
Ambient Temperatures ◽  
Plastic Bags ◽  
Flow Through

SUMMARYAn investigation into two cases of post-operative Bacillus cereus meningitis revealed that hospital linen laundered by a batch continuous washing machine was heavily contaminated by B. cereus spores. The washing machine, detergents, other chemical additives and the water supply were eliminated as the source of contamination.It was found that the linen introduced into the washing machine had a high B. cereus spore content and that this was still present after the wash process. The spores were not killed by either the heat disinfection stage of the wash or the addition of chemical disinfectants and were not removed by the dilution in the process.The multiplication of B. cereus was thought to have occurred on used, damp linen stored in plastic bags, particularly when ambient temperatures were high. An increase in the water flow through the washing machine was the only measure associated with a decrease in B. cereus on laundered linen.

scholarly journals Contribution to study of the dependability of a drinking water system

2018 ◽  
Vol 38 (1) ◽  
pp. 11-18
Author(s):  
Djamila Boumelita ◽  
Lahbassi Ouerdachi ◽  
Nasr-Eddine Debbache
Keyword(s):  
Drinking Water ◽  
Water Supply ◽  
Block Diagram ◽  
Water System ◽  
Spatial Modelling ◽  
Structural Aspect ◽  
Drinking Water System ◽  
Criticality Index ◽  
The City

AbstractIn order to ensure better availability of water resource to different users, we undertook a dependability study of system for drinking water supply. A real case study was done on the water supply network in the city of El Hadjarin Algeria. We started from the site modelling, which provided a calculation of a Hydraulic Criticality Index (HCI) in order to prioritize the importance of pipes in the network. Once the indices were calculated, a modelling procedure of reliability block diagram was applied. The objective was to study and analyse the existing network to measure the water availability problems and try to provide viable solutions. An action on the structural aspect and hardware may be required in order to ensure better availability of water and make the system more reliable. Spatial modelling is also proposed to be able to monitor different parts of the network where problems may occur.

scholarly journals ANALISIS KINERJA CHILLER DI GEDUNG SENAYAN CITY

2020 ◽  
Vol 1 (1) ◽  
pp. 44-47
Author(s):  
Maya Firanti Putri ◽  
Aris Sunawar ◽  
Massus Subekti
Keyword(s):  
Qualitative Research ◽  
Performance Analysis ◽  
Energy Conservation ◽  
Water Flow ◽  
Cooling Capacity ◽  
Third Party ◽  
Minimum Standards ◽  
Chilled Water ◽  
Minimum Number ◽  
Compressor Power

Abstract. Research conducted in the building Senayan City in June 2016 using qualitative research methods. Standards are used as a benchmark the performance of each chiller uses ISO 6390 in 2011 on Energy Conservation Air system administration Building. These aspects are analyzed to determine the performance of the chiller is the temperature of chilled water, flow chilled water and compressor power. As for the influence of the three aspects is the temperature of the outside environment. By calculating the cooling capacity, the highest Coefficient of Permonace (COP) value can be determined each chiller.Chiller performance analysis results obtained COP value of the highest attainable number 1 at 7.31 chiller, chiller number 2 at 8.03 and chiller number 3 6:27. These values ​​meet the mi nimum value of COP according to ISO standards. Lowest chiller COP value number 1 by 5.08, number 2 for 5.12 chiller and chiller number 3 at 4.22. Third party chiller COP minimum value does not meet the minimum standards of the COP. Chiller number 3 has the lowest minimum number COP and far below the minimum stadar.Judging from the value of cooling capacity and COP, chiller performance is not good enough is the number 3. And the chiller that has good enough performance is number 1 and 2 Abstrak Penelitian ini bertujuan untuk menghasilkan data analisis kinerja chiller di gedung Senayan City. Penelitian yang dilakukan di gedung Senayan City pada bulan Juni 2016 ini menggunakan metode penelitian kualitatif. Standar yang digunakan sebagai patokan kinerja masing-masing chiller menggunakan SNI 6390 tahun 2011 tentang Konservasi Energi Sistem Tata Udara Bangunan Gedung. Aspek-aspek yang dianalisis untuk mengetahui kinerja chiller adalah temperatur chilled water, flow chilled water dan power kompresor. Adapun yang mempengaruhi ketiga aspek tersebut adalah temperatur lingkungan luar. Dengan menghitung kapasitas pendinginan, dapat ditentukan nilai Coefficient of Permonace (COP) tertinggi masing-masing chiller. Hasil analisis kinerja chiller didapat Nilai COP tertinggi yang dapat dicapai chiller nomor 1 sebesar 7,31, chiller nomor 2 sebesar 8,03 dan chiller nomor 3 6.27. Ketiga nilai tersebut memenuhi nilai minimum standar COP menurut SNI. Nilai COP terendah  chiller nomor 1 sebesar 5,08, chiller nomor 2 sebesar 5,12 dan chiller nomor 3 sebesar 4,22. Ketiga nilai minimum COP ketiga chiller ini tidak memenuhi standar minimum COP. Chiller nomor 3 mempunyai angka minimum COP paling rendah dan jauh dibawah stadar minimum. Dilihat dari kapasitas pendinginan dan nilai COP, chiller yang kinerja kurang baik adalah chiller nomor 3. Dan chiller yang performanya cukup baik adalah chiller nomor 1 dan 2.

Fuzzy Control for Variable Cooling Water Flow System

2012 ◽  
Vol 461 ◽  
pp. 105-108 ◽  
Author(s):  
Jin Ming Yang
Keyword(s):  
Control System ◽  
Water Flow ◽  
Frequency Conversion ◽  
Control Strategies ◽  
Water System ◽  
Cooling Water ◽  
Variable Flow ◽  
Control Loops ◽  
Cooling Water System ◽  
And Control

The variable flow cooling water system can achieve energy saving benefits just like variable primary flow chilled water system for central air conditioning system. How to design the control system with appropriate control algorithms and control strategies is particularly important. We can clarify the basic control principle of variable cooling water flow technology based on the analysis on DOF (degree of freedom) of cooling water systems, it is important for control system design. The article pointed out explicitly that the realization of variable flow technology for cooling water system must construct two control loops, one for cooling water supply temperature the other for return temperature, further more discussed control strategies for two control loops. In the end the article illustrated the synchronous frequency conversion technology for multiple cooling water pumps system to avoid overload when part of pumps put in operation

scholarly journals Flow dynamics in a vadose shaft – a case study from the Hochschwab karst massif (Northern Calcareous Alps, Austria)

2021 ◽  
Vol 50 (2) ◽  
pp. 157-172
Author(s):  
Eva Kaminsky ◽  
Lukas Plan ◽  
Thomas Wagner ◽  
Barbara Funk ◽  
Pauline Oberender
Keyword(s):  
Water Flow ◽  
Vadose Zone ◽  
Average Delay ◽  
Small Catchment ◽  
Diffuse Infiltration ◽  
Lumped Parameter ◽  
Flow Through ◽  
Rainfall Runoff Model ◽  
Water Transmission

Karst aquifers are highly vulnerable to contamination due to quick water flow through conduits. Their high heterogeneity and the poorly known infiltration effect of the vadose zone make quantification of recharge processes difficult. This study characterizes the water flow and storage in the upper vadose zone with almost four years monitoring of a permanent stream in a vadose shaft (Furtowischacht). Its small catchment of 4,500 m² is located in a former glaciated high Alpine environment (Hochschwab, Austria). High discharge fluctuations between 0.002 and 19 l/s, relatively high hydrograph recession coefficients, and transit velocities between 0.0015 and 2.4 m/s estimated with salt tracer experiments indicate a highly dynamic discharge behavior. A fast point infiltration through open karren and dolines could be observed for rainfall events and indicates a highly karstified network with a rapid water transmission. Snowmelt periods show only a slower flow component and diffuse infiltration. However, condensation within the conduit system is likely superimposed to this signal. A lumped-parameter rainfall-runoff model is used to simulate the discharge with a dual porosity approach. It indicates a low storage volume, which is in accordance with the estimated storage of 22 m³ (or 5 mm), deduced from the recession analyses. In contrary, the physicochemical parameters argue for some storage capability: 1) After an increase of discharge, electric conductivity reacts with an average delay of 50 min; 2) Partly a piston flow can be recognized. These amounts of water may be stored in the partial soil cover alone and therefore the presence of a hydrologically significant epikarst layer is unclear.

scholarly journals Theoretical Prediction of Optimum Chilled Water Distribution Configuration in Air Conditioning Terminal Unit

2019 ◽  
Vol 14 (2) ◽  
pp. 137-146
Author(s):  
Ahmed Abd Mohammed Saleh ◽  
Ali Reyadh Shabeeb
Keyword(s):  
Standard Deviation ◽  
Water Supply ◽  
Water Flow ◽  
Flow Rate ◽  
Air Conditioning ◽  
Water Flow Rate ◽  
Total Water ◽  
Terminal Unit ◽  
Chilled Water ◽  
Valve Opening

 The distribution of chilled water flow rate in terminal unit is a major factor used to evaluate the performance of central air conditioning unit. In this work, a theoretical chilled water distribution in the terminal units has been studied to predict the optimum heat performance of terminal unit. The central Air-conditioning unit model consists of cooling/ heating coil (three units), chilled water source (chiller), three-way and two-way valve with bypass, piping network, and pump. The term of optimization in terminal unit ingredient has two categories, the first is the uniform of the water flow rate representing in statically permanents standard deviation (minimum value) and the second category is the maximum heat transfer rate from all terminal units. The hydraulic and energy equations governing the performance of unit solved with the aid of FORTRAN code with considering the following parameters: total water flow rate, chilled water supply temperature, and variable valve opening. It was found that the optimum solution of three-way valve case at 8°C water supply temperature, 0.12 kg/s total water flow rate and valve opening order (valve 1: 100%, valve 2: 100% and valve 3: 75%) with total heat rate (987.92 Watt) and standard deviation (1.181E-3). Also, for the two-way valve case the results showed that the optimum condition at 8°C water supply temperature, 0.12 kg/s total water flow rate and valve opening order (valve 1: 75%, valve 2: 75% and valve 3: 50%) with total heat rate and standard deviation (717Watt) and (5.69E-4) respectively.

scholarly journals Sustainability of Rural Water Supply Systems: A Case Study of Kwamekrom Water System in the Volta Region of Ghana

2019 ◽  
Vol 12 (5) ◽  
pp. 30
Author(s):  
Patrick Adadzi ◽  
Harrison Coffie ◽  
Emmanuel Afetorgbor
Keyword(s):  
Water Supply ◽  
Rural Areas ◽  
Financial Management ◽  
Water System ◽  
Water Systems ◽  
Water Supply Systems ◽  
Rural Water Supply ◽  
Rural Water ◽  
Volta Region

This paper review and analyze the sustainability of rural water systems facilitated by Community Water and Sanitation Agency (CWSA) in Ghana in both their capacity to continue to deliver adequate, safe and quality water for all the people of Kwamekrom township and surrounding villages. The paper focus on a case study of the sustainability of small-town piped water systems; the main used technology in rural areas of the Volta Region in Ghana. Part of the project was the implementation of infrastructure and building capacities in the community to manage and use their system after project completion. A recent development is that CWSA is shifting from community ownership and management (COM) towards participation in management, a shift that is expected to ensure the sustainability of the water systems. The study aimed to analyze the viability of the Kwamekrom water supply system in the Volta Region of Ghana, which was under the COM system utilizing a survey mechanism. The study revealed based on performance indexes indicated that the Kwamekrom water system was not sustainable under the COM. The result was mainly due to poor financial management and lack of adequate technical expertise coupled with socio-political impact under the COM. The new reform towards participation in the management of rural water supply is, therefore, an approach which could lead to sustainability.

Performance indicators for water supply management

2015 ◽  
Vol 15 (4) ◽  
pp. 718-726 ◽  
Author(s):  
Ruggero Ermini ◽  
Rafet Ataoui ◽  
Lydra Qeraxhiu
Keyword(s):  
Water Supply ◽  
Performance Indicators ◽  
Water System ◽  
Supply System ◽  
Operating Conditions ◽  
Level Of Service ◽  
Water Supply Management ◽  
Specific Performance ◽  
Over Time

In the present study specific performance indicators are proposed that express the level of service of a water system subjected to varying operating conditions over time. The proposed methodology has been applied to a specific case study (Sinni water supply system in Basilicata – Italy) to demonstrate the real applicability of the proposed performance analysis that could be very useful to support the monitoring and the management activities.

Chiller Condenser Service Water Cooling Valve Maintenance

2008 ◽  
Author(s):  
Ken Boughton ◽  
Paul N. Hansen
Keyword(s):  
Flow Control ◽  
Water Flow ◽  
Water System ◽  
Cooling Water ◽  
Control Valves ◽  
Service Water ◽  
Low Load ◽  
Chilled Water ◽  
Chilled Water System ◽  
Load Conditions

This paper presents issues associated with Chilled water system operations at a Nuclear facility that experiences problems with the cooling water flow control valves during the cold season under low load conditions. The system is used to provide safety related functions of cooling rooms such as the control rooms due to radioactive and toxic gas hazards. The valves experience excessive cycling under low load conditions during the cold seasons leading to maintenance and availability problems with the system. This problem is driven by the current system design and the need to utilize a chilled water system during times when natural ambient temperature conditions are low. The Chilled water system uses refrigeration units to cool the chilled water and service water to provide the heat sink for the refrigeration condensing units. The focus of the discussion is the cooling water (service water) flow control valves, which are the major source of the maintenance problem. The paper presents the integrated behavior of the Chilled water system to properly characterize the issue and the solutions. The paper will present the system details and performance parameters necessary to evaluate the problem. The behavior of the valves will be evaluated based on the system operations. This paper evaluates the technical merits of several options to provide stable control of the flow control valves, prevent high-pressure chiller unit trips and solve flow control valve actuator excessive wear.

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