AHRI GUIDELINE T I-P-2013 Specifying the Thermal Performance of Cool Storage Equipment.pdf

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1、AHRI Guideline T (I-P) 2013 Guideline for Specifying the Thermal Performance of Cool Storage Equipment Price $15.00 (M)/$30.00(NM) Copyright 2013, by Air-Conditioning, Heating, and Refrigeration Institute Printed in U.S.A. Registered United States Patent and Trademark Office IMPORTANT SAFETY DISCLAI

2、MER AHRI does not set safety standards and does not certify or guarantee the safety of any products, components or systems designed, tested, rated, installed or operated in accordance with this standard/guideline. It is strongly recommended that products be designed, constructed, assembled, installe

3、d and operated in accordance with nationally recognized safety standards and code requirements appropriate for products covered by this standard/guideline. AHRI uses its best efforts to develop standards/guidelines employing state-of-the-art and accepted industry practices. AHRI does not certify or

4、guarantee that any tests conducted under the standards/guidelines will not be non-hazardous or free from risk. Note: This guideline supersedes AHRI Guideline T-2002. For SI, see AHRI Guideline T (SI)-2013. FOREWORD Thermal energy storage (TES) is a proven technology which enables the use of lower co

5、st, off-peak electricity (usually at night) to produce and store cool energy. This cool energy in storage is used the next day for air-conditioning or process cooling. With TES, relatively small equipment operates at night, reducing the use of expensive electricity during the day. The types of equip

6、ment used in connection with this technology may vary widely. Unlike most air-conditioning and refrigeration equipment, Thermal Storage Devices have no sustained, steady-state operating point which can be used to characterize the product performance. Similarly, the usable capacity of a particular Th

7、ermal Storage Device may vary appreciably with the application. For example, very high loads discharged over a short period, and/or relatively low discharge temperatures may reduce the usable capacity to a fraction of the nominal value. These intrinsic characteristics of Thermal Storage Equipment ca

8、n add complexity to the tasks of rating, selecting and specifying such devices. This guideline has been prepared by the Air-Conditioning, Heating and Refrigeration Institute to establish a common, consistent nomenclature and terminology for the industry, and to set forth the minimum performance info

9、rmation that designers should include in their specifications and manufacturers should provide in their proposals for Thermal Storage Equipment. In addition, all of the member manufacturing companies in the AHRI Thermal Storage Equipment product section are available to assist the designer in proper

10、ly specifying the product. TABLE OF CONTENTS SECTION PAGE Section 1. Purpose . 1 Section 2. Scope 1 Section 3. Definitions 1 Section 4. Classifications 3 Section 5. Minimum Information Recommendations . 4 TABLES Table 1. Classification of Cool Storage Equipment . 4 FIGURES Figure 1. Cool Storage Sys

11、tem 2 APPENDICES Appendix A. References - Normative . 7 Appendix B. References - Informative 7 Appendix C. User-Specified Application Recommendations Data - Informative 8 Appendix D. Sample User-Specified Applications Recommendations Data - Informative 9 Appendix E. Supplier-Specified Thermal Perfor

12、mance Data - Informative . 10 Appendix F. Supplier-Specified Thermal Performance Data for Unitary Thermal Storage Systems - Informative 12 Appendix G. Sample Supplier-Specified Thermal Performance Data - Informative 13 Appendix H. Sample Supplier-Specified Thermal Performance Data for Unitary Therma

13、l Storage Systems - Informative . 15 TABLES FOR APPENDICES Table C1. Recommended Specification Information Example 8 Table C2. Preferred User-specified Data Example Design Day . 8 Table D1. Recommended Specification Information Sample 9 Table D2. Preferred User-specified Data Sample Design Day . 9 T

14、able E1. Supplier-specified Data . 10 Table F1. Supplier-specified Data for Unitary Thermal Storage Systems 12 Table G1. Supplier-specified Data - Sample . 13 Table H1. Supplier-specified Data for Unitary Thermal Storage Systems - Sample . 15 AHRI GUIDELINE T (I-P) 2013 1 GUIDELINE FOR SPECIFYING TH

15、E THERMAL PERFORMANCE OF COOL STORAGE EQUIPMENT Section 1. Purpose 1.1 Purpose. The purpose of this guideline is to establish the minimum information required for specifying cool storage equipment: a. User-specified application recommendations b. Supplier-specified thermal performance data 1.1.1 Int

16、ent. This guideline is intended for guidance of the industry, including manufacturers, engineers, installers, contractors and users. 1.1.2 Review and Amendment. This guideline is subject to review and amendment as technology advances. Section 2. Scope 2.1 Scope. This guideline applies to Thermal Sto

17、rage Equipment, for use in cooling systems, which may be charged and discharged with any of a variety of heat transfer fluids, and is either fully factory assembled, assembled on site from factory supplied components or field erected in accordance with pre-established design criteria, all as further

18、 described in Sections 3 and 4. 2.2 Exclusions. This guideline does not apply to Thermal Storage Equipment with thermal storage capacities of 7 ton-hours or less. Section 3. Definitions All terms in this document will follow the standard industry definitions in the ASHRAE Wikipedia website (http:/wi

19、ki.ashrae.org/index.php/ASHRAEwiki) unless otherwise defined in this section. 3.1 Ambient Air. The air in the space surrounding the thermal energy storage device. 3.2 Ambient Heat Load. The load (typically expressed in tons) imposed on the storage device due to heat gain from the ambient. 3.3 Charge

20、 Fluid. The heat transfer fluid used to remove heat from a thermal storage device. 3.4 Charge Period/Cycle. The period of time when energy (heat) is removed from the storage device. 3.5 Charge Rate. The rate (typically expressed in tons) at which energy (heat) is removed from the storage device duri

21、ng the charge period. 3.6 Discharge Fluid. The heat transfer fluid used to add heat to the thermal storage device. 3.7 Discharge Period/Cycle. The period of time when energy (heat) is added to the storage device. 3.8 Discharge Rate. The rate (typically expressed in tons) at which energy (heat) is ad

22、ded to the storage device during the Discharge Period. 3.9 Initial Charge Cycle. The elapsed time required to bring the storage device from ambient conditions to its fully charged condition and the minimum temperature of the Heat Transfer Fluid attained during the cycle. 3.10 Latent Heat of Fusion.

23、The change in enthalpy accompanying the conversion of a unit mass of a solid to a liquid at its melting point at constant pressure and temperature. AHRI GUIDELINE T (I-P) 2013 2 3.11 Net Storage Inventory. Net accumulated measured storage capacity at a given period of time during a 24 hour cycle. 3.

24、12 Net Usable Storage Capacity. The amount of stored cooling, that can be supplied from the storage device at or below the specified cooling supply temperature for a given Charge and Discharge Cycle, typically expressed in ton-hours. 3.13 Nominal Storage Capacity. A theoretical capacity of the stora

25、ge device as defined by the storage device manufacturer (which in most cases is greater than the Net Usable Storage Capacity) typically expressed in ton-hours. 3.14 Phase Change Material (PCM). A substance that undergoes changes of phase while absorbing or rejecting thermal energy, normally at a con

26、stant temperature. 3.15 Saturated Evaporator Temperature. The dew point temperature of the refrigerant corresponding to the saturation pressure at the outlet connection of the evaporator. 3.16 Secondary Coolant. Any liquid cooled by a refrigerant and used for heat transmission without a change in st

27、ate, having no flash point or a flash point above 150F. 3.17 Sensible Heat. Heat that causes a change in fluid temperature. 3.18 Should. This term is used to indicate provisions which are not mandatory but which are desirable as good practice. 3.19 Thermal Storage Device. Equipment which stores cool

28、ing capacity using sensible and/or latent heat. May consist solely of a storage means or be packaged with one or more components of a mechanical refrigeration system. 3.20 Thermal Storage Equipment. Any one of, or a combination of, Thermal Storage Devices and/or Generators, that may include various

29、other components of a mechanical or absorption refrigeration package, as indicated in Section 4. Also referred to as “Cool Storage Equipment.” 3.21 Thermal Storage System. All of the equipment installed to meet a specified Thermal Storage System Load which may include mechanical or absorption refrig

30、eration equipment, see Figure 1. 3.22 Thermal Storage System Load (or Load). A specified cooling load to be met by the Thermal Storage System. Typically, it is expressed in tons (often referred to in this guideline as “the Load“). 3.23 Ton-Hour. A quantity of thermal energy equal to 12,000 Btu or 1.

31、0 ton of refrigeration provided for one hour. 3.24 Unitary Thermal Storage System (UTSS). An assembly of components including a thermal storage device and refrigeration equipment for charging, whose overall performance as a Unitary Thermal Storage System is rated by the manufacturer. Figure 1. Cool

32、Storage System AHRI GUIDELINE T (I-P) 2013 3 Where: T1= Temperature of coolant supplied to the Load T2= Temperature of coolant returning from the Load T3= Temperature of coolant entering the Cool Storage Device. T4= Temperature of coolant leaving the Cool Storage Device. Option A, B, C: Mechanical o

33、r Absorption Refrigeration Equipment (chiller) Section 4. Classifications 4.1 Classification. Thermal Storage Equipment is broadly classified as either “sensible“ or “latent“, with further delineations as shown in Table 1 and explained in subsequent paragraphs. 4.1.1 Sensible Thermal Storage Equipme

34、nt. Sensible Thermal Storage Equipment used for cooling typically employs water as the storage medium. During the Charge Period, warm water from the storage device is chilled to the desired temperature by a water chiller and returned to the storage vessel. During the Discharge (cooling) Period, the

35、chilled water is pumped from the storage vessel to the load and the resultant warm water returned to storage. Any of several methods may be used to keep the warm return water separated from the stored chilled water, including separate or compartmentalized tanks or where only one tank is employed, la

36、byrinths, membranes, or thermal stratification. 4.1.2 Latent Thermal Storage Equipment. Latent Thermal Storage Equipment is further categorized as ice-on-coil, encapsulated ice or Phase Change Material, or unitary. 4.1.2.1 Ice-on-Coil. A Thermal Storage Device consisting of coils, plates, or other h

37、eat transfer surface submerged in a water filled tank. During the Charge Period, an evaporating refrigerant or cold Secondary Coolant is circulated through the coils/plates causing ice to form on the external surfaces. During the Discharge (cooling) Period, either of two methods is typically employe

38、d: 4.1.2.1.1 External Melt. With external melt, warm, return water is circulated through the tank, external to the ice formation, whereby it is cooled by the melting ice. Some ice-on-coil devices may also serve as water chillers by circulating warm return water through the tank and over the external

39、 surface of the heat exchanger where it is cooled by Secondary Coolant or refrigerant circulating within the exchanger. 4.1.2.1.2 Internal Melt. With internal melt, typically a warm, return, Secondary Coolant is circulated through the coils/plates and cooled as the ice external to the coils/plates i

40、s melted. 4.1.2.2 Encapsulated Ice or Phase Change Material. Thermal Storage Equipment consisting of a tank or vessel densely packed with numerous, relatively small containers in which the storage medium (water-ice or other Phase Change Material such as eutectic salt) is encapsulated. During the Cha

41、rge Period, water or Secondary Coolant, at a temperature below the phase change temperature of the storage, media is circulated through the tank/vessel to effect a phase change (freezing) in the storage medium. During the Discharge Period, warm return water or Secondary Coolant is circulated through

42、 the tank/vessel and cooled as the encapsulated storage media changes phase (melts). 4.1.2.3 Unitary. An assembly of components including a thermal storage device and refrigeration equipment for charging which is rated by the manufacturer as a UTSS. The Thermal Storage Device consists of a heat exch

43、anger submerged in a water filled tank. During the Charge Period, an evaporating refrigerant or cold Secondary Coolant is circulated through the heat exchanger causing ice to form on the external surface. During the Discharge (cooling) Period, a condensing refrigerant or warm Secondary Coolant is co

44、oled by internal and/or external melt processes. AHRI GUIDELINE T (I-P) 2013 4 Table 1. Classification of Thermal Storage Equipment Classification Type Storage Media Charge Fluid Discharge Fluid Sensible Chilled Water Water or other Aqueous Solution Water or other Aqueous Solution Water or other Aqu

45、eous Solution Latent Ice-on-Coil (External Melt) Ice or other Phase Change Material Secondary Coolant Water or Secondary Coolant Refrigerant Ice-on-Coil (Internal Melt) Ice or other Phase Change Material Secondary Coolant Secondary Coolant Encapsulated Ice or Phase Change Material Ice or other Phase

46、 Change Material Water Water Secondary Coolant Secondary Coolant Unitary Ice or other Phase Change Material Refrigerant or Secondary Coolant Refrigerant, Water or Secondary Coolant Section 5. Minimum Information Recommendations 5.1 User-Specified Application Recommendations. When specifying the appl

47、ication requirements for cool storage equipment, the user should provide, as a minimum, the following data for a design day (or design week, or other design period): 5.1.1 Thermal Storage System Load for each hour of the design day, tons (referred to as “the Load“ throughout this guideline) 5.1.2 Op

48、erating mode of the Thermal Storage Refrigeration Equipment (charge, partial cooling or off) for each hour of the design day 5.1.3 Design Heat Sink Rejection Temperature, F (information for each hour of the design day is preferred, but not required) 5.1.4 Supply temperature to the Load during the ho

49、ur of maximum load, T1, F (information for each hour of the day is preferred, but not required) (Figure 1) 5.1.5 Return temperature from the Load during the hour of maximum load, T2, F (information for each hour of the day is preferred, but not required) (Figure 1) 5.1.6 Flow rate to the Load during the hour of maximum load or each hour if variable rate pumping is used, gpm 5.1.7 Maximum time available to charge from fully discharged condition, h 5.1.8 Minimum temperature available to charge from fully discharged condition, F 5.1.9 Identify the Charge and