Increasing Efficiency in the Extraction of Solar Heat Stored Underground With Perturb-and-Observe Control

This paper describes a perturb-and-observe (P&O) control aiming to increase the heat exchange between solar heat stored underground and the ambient of a single conditioned room without any heat pump. This P&O control increases or decreases the water flow rate through an underground hosepipe heat exchanger. With this purpose, two power converters were used to activate, respectively, a low power water pump and a fan coil so as to keep the room within the limits of a reference temperature range (between 18 °C and 24 °C). Outside these limits, the P&O control searches for the best heat exchange between the ambient room and the underground soil and, when inside these limits, the water pump and fan coil are turned off. Two identical experimental rooms, referred in this study as “reference” and “test” rooms, had their temperatures measured every 1-min during winter and summer. For comparison purposes, the reference room was left at its natural conditions without any air conditioning. The experimental results show a remarkable improvement in the heat exchange and a considerable reduction in power demand when using the P&O control. As a result, it was obtained an energy saving of approximately 45% in one summer day and 22% in one winter day. It is important to point out that this paper refers, strictly, to the description of a P&O control for heat exchange systems involving solar heat stored underground in a single room.

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Solar Heat Underground Storage Based Air Conditioning Vis-à-Vis Conventional HVAC Experimental Validation

Journal of Solar Energy Engineering ◽

10.1115/1.4038051 ◽

2017 ◽

Vol 140 (1) ◽

Cited By ~ 1

Author(s):

Carlos R. de Nardin ◽

Felipe T. Fernandes ◽

Adriano J. Longo ◽

Luciano P. Lima ◽

Felix A. Farret ◽

...

Keyword(s):

Air Conditioning ◽

Heat Pumps ◽

Conventional Heating ◽

Management Technique ◽

Air Conditioner ◽

Heat Management ◽

Air Conditioners ◽

Solar Heat ◽

Reduction Of Energy Consumption ◽

The One

This paper presents a comparison of air conditioners using the conventional heating, ventilation, and air conditioning heat pumps and the one using solar heat stored underground, also known as shallow geothermal air conditioning. The proposed air conditioner with solar heat stored underground reunites practical data from an implementation of the heuristic perturb-and-observe (P&O) control and a heat management technique. The aim is to find out the best possible heat exchange between the room ambient and the underground soil heat to reduce its overall consumption without any heat pump. Comparative tests were conducted in two similar rooms, each one equipped with one of the two types of air conditioning. The room temperature with the conventional air conditioning was maintained as close as possible to the temperature of the test room with shallow geothermal conditioning to allow an acceptable data validation. The experiments made both in the winter of 2014 and in the summer of 2015 in Santa Maria, South Brazil, demonstrated that the conventional air conditioner consumed 19.08 kWh and the shallow geothermal conditioner (SGC) consumed only 4.65 kWh, therefore, representing a reduction of energy consumption of approximately 75%.

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Energy efficiency of variable frequency water pump in building air conditioning system

2012 2nd International Conference on Consumer Electronics, Communications and Networks (CECNet) ◽

10.1109/cecnet.2012.6202203 ◽

2012 ◽

Cited By ~ 1

Author(s):

Wei Cai ◽

Huang Wang ◽

Wenjun Chen ◽

Maidun Ma

Keyword(s):

Energy Efficiency ◽

Air Conditioning ◽

Variable Frequency ◽

Water Pump ◽

Air Conditioning System

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Effective Fuel Consumption by Improving Cooling Water Flow Rate in IC Engine

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.812.112 ◽

2015 ◽

Vol 812 ◽

pp. 112-117

Author(s):

K.M. Kumar ◽

P. Venkateswaran ◽

P. Suresh

Keyword(s):

Flow Rate ◽

Cooling System ◽

Water Flow Rate ◽

Research Work ◽

Cooling Water ◽

Major Change ◽

Clear Understanding ◽

Water Pump ◽

Ic Engine ◽

Cooling Water Flow Rate

The coolant (water) pump assumes an important role of cooling system in IC engines. With upgrading of the engine power by turbocharging and turbo inter cooling, the water pump capacity needs to be increased corresponding to the power. This capacity enhancement has to be achieved without calling for a major change in the existing water pump, envelop and related fitment details. This requires a clear understanding of centrifugal pump for its performance parameter. One such engine is upgraded by turbocharging from 195PS to 240PS @2200 rpm. Improving water pump flow by changing the impeller dimensions, impeller casing, increase the suction, delivery pipe diameter had been done. Validation of the water pump in its actual engine installation was taken up as a part of the research work. Flow rate comparison of the new pump with the existing pump was made and the results were analyzed. The new water pump gives better flow rates for the engine speeds up to1800 rpm, beyond which the flow rate is slightly lesser than the existing pump.

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On the Energy Efficiency of Indoor Air Conditioning

ENERGETIKA Proceedings of CIS higher education institutions and power engineering associations ◽

10.21122/1029-7448-2019-62-4-325-340 ◽

2019 ◽

Vol 62 (4) ◽

pp. 325-340 ◽

Cited By ~ 1

Author(s):

S. N. Osipov ◽

A. V. Zakharenko ◽

E. M. Shirokova

Keyword(s):

Energy Efficiency ◽

Heat Exchange ◽

Indoor Air ◽

Air Conditioning ◽

Large Scale ◽

Well Being ◽

Physiological Adaptation ◽

Limited Area ◽

Air Conditioner ◽

Conditioning Process

The increase of average outdoor temperatures and their fluctuations over the past 20 years (as evidenced by the records of summer temperatures in our country) has significantly increased the need for air conditioning premises where people are present for a long time, especially when they are crowded (shops, entertainment halls, classrooms, etc.). The air conditioning process is quite energy-intensive, but the growth of well-being in many republics of the former USSR, as well as the increasing complexity of the physiological adaptation of the human body to rising outdoor temperatures make it possible (and at the same time necessary) to implement these systems on a large scale. It is important to take into account that electricity prices are currently maintained at a high level for homeowners, and in the coming years the prices will only grow. Therefore, the development of new ways of significant increase of the energy efficiency of the indoor air conditioning process is of a great interest. One of these methods is the use of laminar (or close to them) moving layers of conditioned air in a limited area of work or rest of people. Such a zone, about 1.0‒1.2 m height from a floor in each apartment is, e.g., living rooms (bedroom) in which standard temperature conditions are created by means of simple air supplying and air intake devices. In the case of sedentary work of people, the height of such a zone of conditioned air should be increased to 1.3‒1.5 m. It has already been established that the use of laminar (or close to them) air flows allows to reduce the power consumption by two or more times due to significantly reduced heat exchange with the surrounding heated surfaces. Besides, the simplicity of such systems ought to be noted. In particular, in conditions of modern systems of control and management of air conditioning, the "duties" of consumers include only the installation on the control device of the initial data relating directly to the required parameters of the microclimate. At the same time, it should be noted that there is currently no complete scientific and technical description of aerodynamic and heat exchange processes in the air conditioning zone. Even in modern conditions for countries with a sharply continental climate (Russia, Kazakhstan, etc.), the problem is the choice of the type of air conditioner for its effective use in hot periods of summer. In general, it can be noted that all the problems of energy-efficient use of air conditioners must find a comprehensive solution.

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The Analysis of Modifications in Cooling Systems for High-Performance Data Centers. A Case Study

Proccedings of 10th International Conference "Environmental Engineering" ◽

10.3846/enviro.2017.273 ◽

2017 ◽

Author(s):

Artur Rusowicz ◽

Adam Ruciński ◽

Rafał Laskowski

Keyword(s):

Air Conditioning ◽

High Performance ◽

Energy Savings ◽

Cooling System ◽

Capital Expenditure ◽

Cooling Power ◽

Power Demand ◽

Excessive Heat ◽

Refrigeration Equipment ◽

Payback Time

One of main issues concerning server room operation is appropriate cooling of electronic modules to prevent excessive heat generation resulting in their damage. Since high cooling powers are required, precision air conditioning systems are used that are specially designed for cooling server and equipment rooms, server cabinets, etc. These devices require very large energy supplies. The paper proposes an upgrade of a cooling system for three server rooms in which refrigeration equipment with a cooling power of 1.873 MW is installed. The average actual cooling power demand is 890 kW, and some units work as a standby. Thir-eight direct-evaporation air-conditioning cabinets are installed. The refrigerant is R407C. The devices have been operated for 14 years; therefore, the refrigeration equipment should be replaced with modern units. The paper compares three approaches: replacing the units with similar ones based on newer technology, introducing contained aisle configurations of rack cabinets and units based on newer technology with additional EconoPhase modules. The application of free cooling was not analyzed since mounting additional heat exchangers was impossible (due to the lack of space and limited roof loading capacity). The paper provides capital and operating costs of the solutions. The introduction of up-to-date units and replacing condensers resulted in lowering the electric power demand by 16%. The simple payback time (SPBT) of this solution is 18.8 years. The energy savings achieved through the second solution (contained aisle configurations of rack cabinets) amount to 37.8%, with SPBT equal to 8.38 years. Variant III, consisting in using modern units with additional EconoPhase modules, significantly improves energy savings (48.3%) but it requires large capital expenditure, with simple payback time of 12.1 years.

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Research on Heat Transfer Performance of Micro-Channel Backplane Heat Pipe Air Conditioning System in Data Center

Applied Sciences ◽

10.3390/app10020583 ◽

2020 ◽

Vol 10 (2) ◽

pp. 583

Author(s):

Liping Zeng ◽

Xing Liu ◽

Quan Zhang ◽

Jun Yi ◽

Xianglong Liu ◽

...

Keyword(s):

Heat Transfer ◽

Heat Exchange ◽

Heat Pipe ◽

Temperature Difference ◽

Air Conditioning ◽

Heat Transfer Performance ◽

Transfer Performance ◽

Micro Channel ◽

Filling Rate ◽

Air Conditioning System

This paper deals with the heat transfer performance of a micro-channel backplane heat pipe air conditioning system. The optimal range of the filling rate of a micro-channel backplane heat pipe air conditioning system was determined in the range of 65–75%, almost free from the interference of working conditions. Then, the influence of temperature and air volume flow rate on the heat exchange system were studied. The system maximum heat exchange is 7000–8000 W, and the temperature difference between the inlet and outlet of the evaporator and the condenser is almost 0 °C. Under the optimum refrigerant filling rate, the heat transfer of the micro-channel heat pipe backplane system is approximately linear with the temperature difference between the inlet air temperature of the evaporator and the cooling distribution unit (CDU) inlet water temperature in the range of 18–28 °C. The last part compares the heat transfer characteristics of two refrigerants at different filling rates. The heat transfer, pressure, and refrigerant temperature of R134a and R22 are the same with the change of filling rate, but the heat transfer of R134a is lower than that of R22. The results are of great significance for the operational control and practical application of a backplane heat pipe system.

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Flow Resistance Coefficient Identification of Chilled Water System Based on Multi-Objective Optimization and Experiment Validation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.651-653.742 ◽

2014 ◽

Vol 651-653 ◽

pp. 742-746

Author(s):

Zhi Jian Hou ◽

Ming Qu ◽

Zhi Rui Wang

Keyword(s):

Flow Rate ◽

Air Conditioning ◽

Optimization Problems ◽

Water Flow Rate ◽

Resistance Coefficient ◽

Fundamental Parameter ◽

Multi Objective Optimization ◽

Air Conditioning System ◽

Multi Objective ◽

Terminal Unit

Hydraulic resistance coefficient (HRC) is a fundamental parameter that characterizes the hydraulic state of a water pipeline and significantly determines the efficiency of the water-transport process. To estimate HRC and diagnose hydraulic process fault in building air conditioning system, a novel method called multi-objective optimization (MBO) strategy was developed in the research effort. MBO is concerned with mathematical optimization problems involving more than one objective function to be optimized simultaneously. In this paper, first, the basic principle of the approach is presented. Then several experiments are conducted to identify the HRC in a real air conditioning system. And the water flow rate of each air handling terminal unit is estimated by the flow rate of primary pipe and identified HRC. The experiment results show that the model can accurately estimate HRCs. The HRCs of each pipe and terminal unit were obtained by the flow rate and the pressure difference of primary pipe without requiring geometric specifications, which is very convenient in real engineering application.

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Research on Intelligent Air Conditioning System of Data Center

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.602-605.928 ◽

2014 ◽

Vol 602-605 ◽

pp. 928-932

Author(s):

Min Li ◽

Yun Wang ◽

Zheng Qian Feng ◽

Wang Li

Keyword(s):

Heat Exchange ◽

Energy Saving ◽

Data Center ◽

Air Conditioning ◽

Data Centers ◽

Cooling Efficiency ◽

Exchange System ◽

Air Conditioning System ◽

Running Time ◽

Heat Exchange System

By studying the energy-saving technologies of air-conditioning system in data centers, we designed a intelligent air conditioning system, improved the cooling efficiency of air conditioning system through a reasonable set of hot and cold aisles, reduced the running time of HVAC by using the intelligent heat exchange system, an provided a reference for energy saving research of air conditioning system of data centers.

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