<< The ASHRAE Handbook (2006) reports different tables to design the liquid lines as a function of the system capacity, refrigerant and tube material, for fixed temperature change of 0.02 K m-1in the case of liquid line and for liquid velocity of 0.5 m s ⦠The resulting high discharge/low suction pressure condition will result in more liquid refrigerant in the accumulator. Liquid Line. The ASHRAE Handbook – Refrigeration (2006) suggests a complete procedure for refrigerant line sizing including several tables for different halocarbons refrigerants and ammonia. - < 1°F to 2°F, < 300 fpm. Therefore, a successful refrigeration system also depends on good piping design. , the accumulator holding capacity should be about 70% of the system charge. UNILAB S.R.L. From this overview, it clearly appears that the design of suction and discharge lines is a little bit different from that of the liquid lines; the first one is guided by an energy efficiency criterion while the latter follows technological considerations. Suction Line. A suction line provides refrigerant gas tothe suction connection of the compressor. A R134a refrigeration system using copper pipe operates at 5 °C evaporator and 40 °C condensing. Since the topic includes several interesting aspects, it will be subdivided in three parts: the first one will introduce the general principles of refrigerating line sizing and then will describe the procedure for the liquid lines, the second part will explain the suction and discharge design procedure, whereas the last one will be devoted to the oil management in refrigerant lines. For Heat Pump systems, the chart below shows when an application is considered Long Line: HP with Puronr Refrigerant Long Line Description ft (m) (Beyond these lengths, long line accessories are required) Liquid Line Size Units On Same Level Outdoor Below Indoor Outdoor Above Indoor 3/8 + TXV 80 (24.4) 20 (6.1) vertical or 80 (24.4) total 80 (24.4) For long line installations over 80 feet, if the line set passes through a high ambient temperature zone, 1/2â thick suction line insulation is required to reduce loss of capacity. 1 0 obj If the same system included a riser of 4 m, the design procedure should also account for this additional pressure drop: Δpr= 11,3 ・L = 11.3 ・4= 45.2 kPa=45200 Pa. The size of this pipe can be 3/8â up to 25 tons capacity, and 1/2â up to 60 tons. Refrigerating systems are normally designed so that pressure drop in the liquid line from friction is not greater than that corresponding to about a 0.5 to 1 K change in saturation temperature. This reveals a compromise that the system designer must deal with. The following paragraphs will describe the liquid line design procedure. The equivalent lengths for fitting are listed in special tables reported by ASHRAE handbook (2006). /OPM 1 If multiple line sets are routed through a common conduit, then all lines must be insulated. pounds 3/8â 3.6 Refrigerant Piping Design Goals A common goal is to size the Suction, Hot Gas and Liquid lines for about 1Fº pressure drop at design capacity. There are also other important issues directly linked to the piping system; among those, it should ensure the oil return to the compressor, preventing excessive amounts of lubricating oil from being trapped in any part of the system; prevent liquid refrigerant or oil slugs from entering the compressor during operating and idle time. permagum around refrigerant lines where they penetrate a wall to reduce vibration and to retain some flexibility. << The liquid line is full of high-pressure liquid refrigerant. >> The next table illustrates an example of the sizing table for R134a, copper tube; the third column is devoted to the liquid lines, the other refers to suction and discharge lines. The saturation pressure of the R134a at 40°C is 1016.6kPa, thus the net pressure at the inlet of the expansion device is: P=Psat-Δptot=1016.6-72.10=944.5kPa=944500Pa. Capacity is 20 kW and the liquid line is 50 m equivalent length without riser. Example: A 25,000 BTUH load will require a 3/8" line for The USA’s return to the Paris agreement on climate change and its implications, Data Visualisation: the importance of making data accessible, The latest on 5G: environments and applicability. Now, the actual temperature drop ΔT can be calculated as: Where (ΔT/L)Table is the design temperature drop per unit of length, P0 is the cooling capacity and P0,Table is the cooling capacity listed in the table. Considering the condensation pressure, it is possible to calculate the final pressure at the inlet of the throttling device and verify if the subcooling is enough to avoid the gas formation. Economics, pressure drop, noise, and oil entrainment establish feasible and recommended design velocities in refrigerant lines, which are listed in the next table. endobj Divide the total capacity specified by the number of working pumps. References Weight (lbs) 2 of Saturated Refrigerant @ 77°F per 100' Tube O. D. (inches) Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor Liquid Vapor 1/2 7.48 0.28 7.59 0.20 6.56 0.41 7.20 0.31 7.15 0.28 ⦠Figure 1: Suction, Discharge, and Liquid Line Capacities in Kilowatts for R134a (Single- or High-Stage Applications). The liquid line design procedure is the following: using the system capacity and the proper tablefor the considered fluid (see Figure 1), the nominal line diameter is determined. Vaccine passports and travel: what will post Covid travel be like? ⢠prevent oil draining from an active to an inactive evaporator when more than one Liquid sub-cooling is the only method that prevents refrigerant flashing to gas due to pressure drops in the line. For the ammonia pumps, the capacity of the line is taken according to the customer specified capacity. Figure 2: Condensing Unit with DX Air Handling Unit DX Air Handling Unit TX Valve Sight Glass Solenoid Valve Filter-Drier Liquid Line Suction Line Air Cooled This drops the pressure of the refrigerant to such a degree, that the saturation temperature is lower than the temperature of the air surrounding the tubing that the refrigerant is in. 2 3 1.1 Pressure R600a 1.2 Capacity R600a The first remarkably large difference between R600a and R134a or R12, is found in the pressure level, which is much lower, e.g. refrigerant r-22 line size; (o.d. Therefore it is essential that the installing contractor understand the eËect of piping and be The velocity at the suction of the pump is taken as 0.5 m/s because it is gravity fed. The refrigeration capacity of a compressor is the product of the evaporator enthalpy rise and the compressor mass flow rate. / in.) Registered office: Via Nino Bixio, 6 – 35131, Padova ITALY V.A.T. If a receiver is used to control the refrigerant charge fluctuation during the operation, this components should be fed with saturated liquid from the condenser and, then, it should feed the liquid to the subcooler to achieve the requested subcooling level. This means you must add refrigerant for 85 feet of 3/8-inch line. >> Simplefooe Ford Refrigerant And Oil Capacity Charts. Acceptable vapor line diameters provide adequate oil return to the compressor while avoiding excessive capacity loss. +39 (0)49 8763311 Fax +39 (0)49 8750196, Refrigerant line sizing – Part I: general principles and liquid lines. Allowable Refrigerant Charge 8 Evaporator Capacity Table 29 Flammable Properties 9 Evaporator Capacity Correction Factors 29 Safety Standards & Code of Practice 9 SECTION 5 Design 10 HC-22a Refrigerant Charge 10 Suction Line 30 HC Refrigerant Equivalents 11 Evaporator Capacity Table 30 Categories 13 Evaporator Capacity Correction Factors 30 You should always attempt to verify the information with your vehicle manual or information provided on the underhood stick, sometimes also located on the top of the accumulator. A R134a refrigeration system using copper pipe operates at 5 °C evaporator and 40 °C condensing. Table 3 shows the inlet volumetric flow rates required to achieve 350 ton of cooling. /Type/ExtGState The subcooling can be achieved using part of the condenser as a subcooler; this implies that part of the condenser will be flooded and will operate as a receiver. /OP true Buick refrigerant and oil capacity charts. Loss caused by risers is approximately 11.3 kPa per metre of liquid lift. Even today, the conversion from R12 to R134a is still an ongoing topic in the area of classic and modern classic cars as well as in several non-EU countries. When the high-pressure liquid hits the small restrictor in the metering device, the pressure is immediately reduced. Refrigerant and oil capacity guides are based on data provided by sources such as AllData and Mitchell. The increase of compressor’s work due to the suction and discharge pressure drops is similar for all fluids and it slightly depends from the line location. Kenworth Hvac Systems. << Compressor / System Refrigerant & Lubricant Specs All oil specifications assume that A/C system has been properly cleaned, and new accumulator / filter drier has been installed. After breaking the vacuum with refrigerant ⦠Δptot=Δpr+Δpf=45.2+26.90=72.10 kPa = 72100Pa. On our website, you will find documentation about our Engineering Software Products, Tutorials, Case Studies written in collaboration with our longstanding customers', and Articles about Thermodynamics, Engineering, and HVAC Market Insights. Capacity is 20 kW and the liquid line is 50 m equivalent length ⦠4 0 obj number: 204909 Ph. 3. Now we look at the chart and see that 1-1/8â³ SUCTION lines take 0.20 ounces for R-410A and 5/8 liquid takes 1.64 ounces of R-410A. - Pitched 1/2" per 100 ft. toward compressor (horizontal) - You only need to figure suction riser if compressor is above the evaporator. (Here is a link to an electronic scale.) Obviously, the piping system should ensure the proper refrigerant feed to evaporator, and maintain a clean and dry system. The use of material contained in this guide has the following limitations: ] Tonnage Per Circuit = 1 thru 20 Tons Refrigeration ] Maximum Equivalent Line Length = 150 Ft. ] Maximum Vertical Rise = See Equipment Layouts, Pg 4 ] Cannot be used for heat Pump Models For assistance in estimating piping requirements and costs outside of these limitations, please contact the factory. / in.) number: IT01334900287 Net Assets Euro 2.356.879,00 On the other hand, it can be easily demonstrated that a rough sizing of the suction, discharge, and liquid lines can lead to a non-negligible efficiency losses. Air conditioning system 2020 super duty chis cab order 2019 how to depreciate property kenworth r134a capacity ford refrigerant and oil capacity charts. >> However, the The line sizes given on the specification sheets are based on a 5 pound pressure drop for the entire piping run, from 50' to 250'. - < 2°F, > 750 fpm (horizontal), > 1500 fpm (suction riser), < 4000 fpm. If subcooling is insufficient, flashing occurs in the liquid line and degrades system efficiency. Missing or damaged refrigerant line insulation insulation On the refrigerant lines, particularly on the larger suction line, will cause condensation and drips from the lines in humid areas. The upper limits are linked to economics, pressure drop, and noise whereas the lower ones to oil entrainment and fouling issues. 2 0 obj The temperature drops can be calculated with the previous equations: with 15 mm tube, the temperature drop is greater than 1 K, thus it is not acceptable, the proper design of this liquid line calls for 18 mm nominal tube diameter. For example, measuring the refrigerant gas line pressure drop (or temperature change) on the suction line (return to the compressor) will show (typically) that a 4 degree temperature loss through the refrigerant line will result in an 8 percent loss in cooling capacity of the system. %PDF-1.3 An energetic criterion can be considered to design the piping system; pressure drop in suction and discharge refrigerant lines reduces system efficiency because,as the saturation pressure decreases, the saturation temperature decreases, accordingly. This provides adequate holding capacity during operation with blocked or fouled heat exchanger coils. >> VAPOR LINE SIZING AND COOLING CAPACITY LOSS Acceptable vapor line diameters provide adequate oil return to the compressor while avoiding excessive capacity loss. Registered R.E.A. << decreases system capacity by about 2.5 percent and decreases system efficiency by about 2 percent. The development and design processes of a refrigerating system are commonly focused on the major components of the machine: compressor, condenser, evaporator, and throttling device; sometimes the role of the piping in the efficiency of a vapour compression system is forgotten or simply, neglected. The actual pressure drop in PSI (kPa) will depend on the refrigerant. >> stream Product Application Compressor type Refrigerant Viscosity Class Contents Part number PAG Oil (can) Vehicle air-conditioning systems* All types** R134a PAG I (ISO 46) 240 ml 8FX 351 213-031 Vehicle air-conditioning systems* All types** R134a PAG II (ISO 100) 240 ml 8FX 351 213-051 pounds 3/8â 3.9 1/2â 7.3 5/8â 11.7 7/8â 24.5 1-1/8â 41.0 1-3/8â 63.0 1-5/8â 90.0 refrigerant r-404a / r-507 line size; (o.d. Three fluids are compared: R134a, propane (R290), and ammonia (R717); the comparisons are carried out considering the separated effects of suction and discharge pressure drops in terms of volumetric cooling capacity and compressor’s work. Finally, an additional consideration must be reported: liquid-line risers are a source of pressure loss and add to the total loss of the liquid line. endobj As shown in the diagram below, the Abscissa is the cooling capacity of the refrigeration system, the ordinate is the flow rate of the refrigerant in the pipeline, and the reasonable flow rate is assumed to be in the range of 5 ~ 20 M / S. Different diameters correspond to different refrigerating capacities and can be selected according to the reasonable range given in the diagram. /Filter/FlateDecode Technical Service Information International Trucks. The liquid line that connects the condenser and the throttling device needs of different considerations; in this case, the pressure drop does not affect the energy efficiency since the aim of the throttling device is to reduce the pressure from the condensation one to the evaporation one. The factory charge will handle up to 15 feet of 3/8-inch line. Specs are for total system capacities. at 40 °C of condensation temperature. As can be seen HFO1234ze(E) requires a 33% (.601/.450) larger volumetric flow rate. line could possibly shorten a compressorâs life-span. Most refrigerant tubing kits are supplied with 3/8â thick insulation on the suction line. Considering the table reported in Figure 1, last column, since the actual capacity is 20 kW, the nominal diameter can be 15 mm (P0,Table=16.30 kW) or 18 mm (P0,Table=28.40 kW). The diameter of the suction line must be small enough that the resulting refrigerant velocity is sufficiently high to carry oil droplets through the pipe. /Type/ExtGState In fact, pressure drop calculations are determined as normal pressure loss associated with a change in saturation temperature of the refrigerant. Determine liquid line size. /Type/ExtGState The small equalizer line from the receiver to the inlet piping of the condenser should have a valve for shutting off the receiver. â¢Suction gas lines allow refrigerant gas from the evaporator to flow into the inlet of the compressor. /SA true Always refer to under hood decal as the primary source for refrigerant and lubricant information. /OP false ASHRAE Handbook, Refrigeration, 2006. For Heat Pump systems, the chart below shows when an application is considered Long Line. When designing a system, the engineer needs to maintain a solid column of liquid refrigerant ⦠NOTE! /Type/ExtGState HP WITH Râ410A REFRIGERANT LONG LINE DESCRIPTION ft (m) Beyond these lengths, long line accessories are required Liquid Line Size Units On Same Level Outdoor Below Indoor Outdoor Above Indoor 3/8 80 (24.4) 20 (6.1) vertical or 80 (24.4) total 80 (24.4) We provide cutting-edge technologies such as Heat Exchanger Design Software and Selection Software to HVAC&R manufacturers worldwide. 5 0 obj /Length 10559 The frictional pressure drop can be calculated as: Δpf= (Δp/L)Table・ L= 538・50 = 26900Pa=26.90 kPa. endobj 3 0 obj If additional refrigerant needs to be added to the system due to an extra long line set run, break the vacuum with the correct amount of refrigerant from the bottle by using an electronic scale. The tables refer to 40°C condensation temperature, for other saturation temperatures, a correction factor must be applied. (Suction lines contain vapor so they never require a lot of additional refrigerant but liquid lines should always be full of liquid so the majority of the additional charge is for the liquid line). %âãÏÓ This pressure corresponds to 37.28 °C of saturation temperature, this means that the refrigerant at the inlet of the liquid line must be at least 2.72 K subcooled to obtain saturated liquid at the inlet of the throttling device; however, 3-4 K of subcooling are preferable. The following examples explain the use of the tables for liquid line sizing. A liquid line supplies liquid refrigerant from the condenser to a thermal expansion (TX) valve adjacent to the coil. As general rule, we can state that proper design of a line for a given refrigerant mass flow rate is the trade off between the initial costs, which raise as the diameter increases, and the run costs that decrease as the diameter increases because the refrigerant pumping power decreases. The actual line size should provide no more than a 2 to 3°F (1.1 to 1.7°C) pressure drop. â¢Undersizing the suction line reduces compressor capacity by forcing it to operate at a lower suction pressure to maintain the desired evaporator temperature. Say you are installing a 3-ton system that holds a factory charge of 7 pounds of R-22 with a 100-foot-long liquid line. Data estimated Year Model Lubricant A3 SERIES (Cont'd) 2. In order to clarify this point, the next table reports some considerations about the effects of refrigerant pressure drop (saturation temperature drop) on the capacity of an ideal refrigerating system, which operates at a 5 °C saturated evaporator temperature with a 40 °C saturated condensing temperature. Unilab SRL is a Heat Transfer Software Development Company with 30 years' of experience in the HVAC&R market. answer is a total liquid capacity of 128.30 lb of R-22 at 70°F.You get the same answer if you divide by the specific volume of liquid For R-22 at 70°F, the specific The design of refrigerant piping systems involves capacity and eËciency, reliability, oil management, refrigerant charge, sound level, liquid refrigerant control, modulation eËectiveness and cost. R134a was and is used as replacement refrigerant besides several "drop-in" refrigerants (refrigerant mixtures). Articles, Coffee Break, Events, News, News & Events. In our photo at above left where refrigerant line insulation is incomplete, the drip stains on the attic floor may well indicate a point at which leak stains or even mold appear on the ceiling below. As described by ASHRAE handbook (2006), liquid subcooling is the only method of overcoming liquid line pressure loss to guarantee liquid at the expansion device in the evaporator. A Suction line must: ⢠return oil from the evaporator to the compressor at minimum system capacity. â¢Oversizing the suction line ⦠Total loss is the sum of all friction losses plus pressure loss from liquid risers. X í[sWrßñ+êÍ ÑS»îåp8212e#PУêhþûóÌ]ÕÕhH´ãsÜC$²ö%wÞs¥/úö*Mî6g!¹;KºÍ?ëîìöì3>BßðÁÿü|V4IÝ$˶ñeÿ1,ûåìë³?ý9MBr}{| ¬fu²Êë³øã>LÞ¾»~¥¿¼ùé_¯ßþåÝù^wvyí§f:õÙéáùéEysxîäõùõß~÷ìù1e3ͬ:>ë"¦i\ÛVËå¢['7ÙÝyH'ký=üq¦CÖNCY¿ÝbÌÑEO÷ùlØÖݦ{ÜζÕc²ºM¶÷ñpÑLÓ c/ÂQ¿9K§yÉÕ:ìi½zêÖçE:Ù.º¶Íuw)ÅßtÇãöUr×=ò[;-Åc²Õ¾¬. endobj Then, the total equivalent length Le from condenser to throttling device or from receiver to subcooler must be estimated, this value is the sum of the straight pipe length and the equivalent length for fitting (elbows, contraction, etc.). The ASHRAE Handbook (2006) reports different tables to design the liquid lines as a function of the system capacity, refrigerant and tube material, for fixed temperature change of 0.02 K m-1in the case of liquid line and for liquid velocity of 0.5 m s-1 for the receiver to condenser connection lines. at -25 °C evaporation roughly 55 % of R134a or 45 % of R12. If there are some risers the additional pressure drops must be accounted and then the total pressure drop can be calculated. 1. What has to be avoided in the liquid line is the gas formation (“flashing”) due to the pressure drops; in other words, pressure drop should not be so large as to cause gas formation in the liquid line. << ⢠Insulate all vapor lines with a minimum of 1/2 inch of foam ⦠Data reported in the table permit to highlight the different effects of the pressure drops of the suction and discharge lines; as expected, the volumetric capacity is much more affected by the suction pressure drop since both the cooling capacity and the suction vapour density decrease. The total pressure drop is given by the sum of these values as.
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