ASHRAE Journal - February 2009 - 34

Electronic Expansion Valves Vs. Thermal Expansion Valves By Renato Lazzarin, Daniele Nardotto, and Marco Noro, Ph.D. S toring cold and frozen foods uses approximately 40% to 50% of electricity in supermarkets. Open vertical display cabinets, in particular, are large users of electrical energy. Many refrigerating machines use thermostatic expansion valves (TEVs). TEVs are the most widespread expansion device, but they have some characteristics that can limit versatility and performance of the machines. For example, this valve requires a minimum pressure drop between condensation and evaporation. This prevents possible advantages of low condenser pressure for air-cooled condensers. A minimum amount of superheating must be provided to avoid possible hunting of the valve. Some plants are more sensitive to negative aspects of TEV regulation because of plant specifics, type of duty, or distribution of cooling load during the year. Refrigerating machinery in supermarkets is just a characteristic example. One solution to the problems of TEV 34 ASHRAE Journal are both at the outlet of the evaporator. The two signals are elaborated by a regulator that controls, in real-time mode, the valve opening. To evaluate the possibilities of using EEV versus TEV, a large supermarket located on the Tirrenic coast of Italy, not far from Pisa in North Italy, was retrofitted with the EEVs installed in parallel to the TEVs to operate the plant alternately with the two technologies.4 A simulation model was developed to compare the two technologies on an annual basis from the energy and economic point of view under different conditions. The comparison was made for three climates: Milano, Roma and Trapani (for which hourly test referAbout the Authors Renato Lazzarin, is a professor at the Department of Management and Engineering, University of Padova, Italy, President AICARR (Italian Society of Heating Refrigerating and Air-Conditioning Engineers) and Commission E1 IIR. Daniele Nardotto, is a doctoral student and Marco Noro, Ph.D., is a researcher at the Department of Management and Engineering, University of Padova, Italy. is the electronic expansion valve (EEV). This electrically driven control device has been studied experimentally and theoretically in recent years,1,2,3 and it is widely available. It controls the refrigerant flow at the evaporator by means of a pressure sensor and a temperature sensor, which ashrae.org February 2009

ASHRAE Journal - February 2009

Table of Contents for the Digital Edition of ASHRAE Journal - February 2009

ASHRAE Journal - February 2009
Contents
Commentary
Industry News
Letters
Meetings and Shows
Feature Articles
     Carbon Dioxide in North American Supermarkets
     Frost on Air-Cooling Evaporators
     Electronic Expansion Valves Versus Thermal Expansion Valves
     Anniversary Feature: Air Handling Unit Design for Energy Conservation
     Redundancy for Data Centers
Building Sciences
Washington Report
InfoCenter
Special Products
Emerging Technologies
People
Products
Classified Advertising
Advertising Index
ASHRAE Journal - February 2009 - ASHRAE Journal - February 2009
ASHRAE Journal - February 2009 - Cover2
ASHRAE Journal - February 2009 - 1
ASHRAE Journal - February 2009 - 2
ASHRAE Journal - February 2009 - Contents
ASHRAE Journal - February 2009 - 4
ASHRAE Journal - February 2009 - Commentary
ASHRAE Journal - February 2009 - Industry News
ASHRAE Journal - February 2009 - 7
ASHRAE Journal - February 2009 - 8
ASHRAE Journal - February 2009 - 9
ASHRAE Journal - February 2009 - 10
ASHRAE Journal - February 2009 - 11
ASHRAE Journal - February 2009 - 12
ASHRAE Journal - February 2009 - 13
ASHRAE Journal - February 2009 - Letters
ASHRAE Journal - February 2009 - 15
ASHRAE Journal - February 2009 - 16
ASHRAE Journal - February 2009 - A1
ASHRAE Journal - February 2009 - A2
ASHRAE Journal - February 2009 - A3
ASHRAE Journal - February 2009 - A4
ASHRAE Journal - February 2009 - A5
ASHRAE Journal - February 2009 - A6
ASHRAE Journal - February 2009 - A7
ASHRAE Journal - February 2009 - A8
ASHRAE Journal - February 2009 - A9
ASHRAE Journal - February 2009 - A10
ASHRAE Journal - February 2009 - A11
ASHRAE Journal - February 2009 - A12
ASHRAE Journal - February 2009 - A13
ASHRAE Journal - February 2009 - A14
ASHRAE Journal - February 2009 - A15
ASHRAE Journal - February 2009 - A16
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ASHRAE Journal - February 2009 - A18
ASHRAE Journal - February 2009 - A19
ASHRAE Journal - February 2009 - A20
ASHRAE Journal - February 2009 - A21
ASHRAE Journal - February 2009 - A22
ASHRAE Journal - February 2009 - A23
ASHRAE Journal - February 2009 - A24
ASHRAE Journal - February 2009 - A25
ASHRAE Journal - February 2009 - A26
ASHRAE Journal - February 2009 - A27
ASHRAE Journal - February 2009 - A28
ASHRAE Journal - February 2009 - A29
ASHRAE Journal - February 2009 - A30
ASHRAE Journal - February 2009 - A31
ASHRAE Journal - February 2009 - A32
ASHRAE Journal - February 2009 - A33
ASHRAE Journal - February 2009 - A34
ASHRAE Journal - February 2009 - A35
ASHRAE Journal - February 2009 - A36
ASHRAE Journal - February 2009 - A37
ASHRAE Journal - February 2009 - A38
ASHRAE Journal - February 2009 - A39
ASHRAE Journal - February 2009 - A40
ASHRAE Journal - February 2009 - Meetings and Shows
ASHRAE Journal - February 2009 -      Carbon Dioxide in North American Supermarkets
ASHRAE Journal - February 2009 - 19
ASHRAE Journal - February 2009 - 20
ASHRAE Journal - February 2009 - 21
ASHRAE Journal - February 2009 - 22
ASHRAE Journal - February 2009 - 23
ASHRAE Journal - February 2009 - 24
ASHRAE Journal - February 2009 - 25
ASHRAE Journal - February 2009 - 26
ASHRAE Journal - February 2009 -      Frost on Air-Cooling Evaporators
ASHRAE Journal - February 2009 - 28
ASHRAE Journal - February 2009 - 29
ASHRAE Journal - February 2009 - 30
ASHRAE Journal - February 2009 - 31
ASHRAE Journal - February 2009 - 32
ASHRAE Journal - February 2009 - 33
ASHRAE Journal - February 2009 -      Electronic Expansion Valves Versus Thermal Expansion Valves
ASHRAE Journal - February 2009 - 35
ASHRAE Journal - February 2009 - 36
ASHRAE Journal - February 2009 - 37
ASHRAE Journal - February 2009 - 38
ASHRAE Journal - February 2009 - 39
ASHRAE Journal - February 2009 -      Anniversary Feature: Air Handling Unit Design for Energy Conservation
ASHRAE Journal - February 2009 - 41
ASHRAE Journal - February 2009 - 42
ASHRAE Journal - February 2009 - 43
ASHRAE Journal - February 2009 - 44
ASHRAE Journal - February 2009 - 45
ASHRAE Journal - February 2009 - 46
ASHRAE Journal - February 2009 - 47
ASHRAE Journal - February 2009 - 48
ASHRAE Journal - February 2009 - 49
ASHRAE Journal - February 2009 - 50
ASHRAE Journal - February 2009 - 51
ASHRAE Journal - February 2009 -      Redundancy for Data Centers
ASHRAE Journal - February 2009 - 53
ASHRAE Journal - February 2009 - 54
ASHRAE Journal - February 2009 - 55
ASHRAE Journal - February 2009 - Building Sciences
ASHRAE Journal - February 2009 - 57
ASHRAE Journal - February 2009 - 58
ASHRAE Journal - February 2009 - 59
ASHRAE Journal - February 2009 - Washington Report
ASHRAE Journal - February 2009 - 61
ASHRAE Journal - February 2009 - InfoCenter
ASHRAE Journal - February 2009 - 63
ASHRAE Journal - February 2009 - 64
ASHRAE Journal - February 2009 - 65
ASHRAE Journal - February 2009 - 66
ASHRAE Journal - February 2009 - 67
ASHRAE Journal - February 2009 - Special Products
ASHRAE Journal - February 2009 - Emerging Technologies
ASHRAE Journal - February 2009 - 70
ASHRAE Journal - February 2009 - 71
ASHRAE Journal - February 2009 - 72
ASHRAE Journal - February 2009 - People
ASHRAE Journal - February 2009 - Products
ASHRAE Journal - February 2009 - 75
ASHRAE Journal - February 2009 - 76
ASHRAE Journal - February 2009 - Classified Advertising
ASHRAE Journal - February 2009 - 78
ASHRAE Journal - February 2009 - 79
ASHRAE Journal - February 2009 - Advertising Index
ASHRAE Journal - February 2009 - Cover3
ASHRAE Journal - February 2009 - Cover4
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