Program Overview. Selection. fields Example. task... Version: /13

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1 ASPlight Accumulator Simulation Program HYDAC Technology GmbH Postfach 1251 D Sulzbach/Saar. Germany Industriegebiet D Sulzbach/Saar, Germany Tel.: +49 (0) 6897/ Fa: +49 (0) 6897/ (Accumulator Technology) OPERATING INSTRUCTIONS ASPlight Table of contents Accumulator Simulation Program Program description... 2 User interface... 3 Overview... 3 Selection fields... 4 Calculation and input parameters... 7 Number pad & result button... 8 Informations and results field Calculation process Eample task Task to calculate V Task to calculate p /13

2 1. Program description ASPlight enables you to calculate the: pressures, volume, temperature as well as pressure and flow ratios of an accumulator, simply by entering e a few accumulator parameters. The calculation is similar to that done on a pocket calculator. Basic knowledge of the operating characteristicss of hydraulic accumulators is required. r The ASPlight is optimised to use on the smartphone. 2/13

2. User interface The user interface for ASPlight is divided into different fields and includes: selection fields, functionn and input fields, as

Overview = Operating gas: = Units: = Echange speed: = Echange direction: = Calculation and input parameters: = Number pad: = Result button: Choice

between chargee and discharge For accumulator parameters such as pressure, volume, temperature Calculation parameters are displayed in red Can be

3 2. User interface The user interface for ASPlight is divided into different fields and includes: selection fields, functionn and input fields, as well as result and information fields. Thiss section describes these fields in more detail Overview = Operating gas: = Units: = Echange speed: = Echange direction: = Calculation and input parameters: = Number pad: = Result button: Choice between N2 (nitrogen), He (helium) and air For temperature, pressure and volume Choice between adiabatic (fast) and isothermal (slow) process Choice between chargee and discharge For accumulator parameters such as pressure, volume, temperature Calculation parameters are displayed in red Can be used for entering values Eample: Calculation V 0 The calculation parameter V 0 is activated = Information field: = Results field: Information about pressure/volume ratio In this case, " V 0 " at T min and T ma 3/13

4 2.2. Selection fields Operating gas The "Operating gas" selection field also offers the selection fields Helium (He) and (Air), in addition to the default gas type (N 2 ) Nitrogen. You can sett the desired gas type here. Hydraulic accumulators must only be charged with nitrogen. Never use oygen or air - Risk of eplosion! If theree are variations, please enquire. Units The physical units for temperature, pressure and volume can c be selected as follows: Temperature: Degrees Celsius ( C), Fahrenheit ( F), Kelvin (K) Pressure: bar, psi, MPa (Mega Pascal) Volume: Litres (L), gallonss (Gal (US)) Click the appropriate button to activate the desired unit. The value that is input or output will then be in this unit. The following overview shows the relationship between the physical unit and the calculation parameter. Physical units Calculation parameters Temperature [ C, F, K] Pressure [bar, psi, MPa] Volume [L, Gal (US)] T ma p 2 V T min p 1 T 0 p 0 V 0 p 0Tmin p 0Tma 4/13

5 Echange direction Hydropneumatic accumulators are generally used for energy storage. The accumulator must provide a certain amountt of energy/fluid at a certain time. This means that it is discharged. discharge Conversely, select charge if the accumulator is to be charged in its application. Both echange directions, both charge and discharge, cann take place quickly or slowly; see Echange Speed. charge 5/13

Echange speed In thermodynamics, there are different changes in

ASPlight is limitedd to the minimum and maimumm valuess for the

change of state = no heat echange withh the environment With this

This option results in large accumulatorr volumes or in smalll V

Isothermal change of state = complete heat echange with the

6 Echange speed In thermodynamics, there are different changes in statee for gases. ASPlight is limitedd to the minimum and maimumm valuess for the calculation: Echange speed in p-v graph Adiabatic (= isentropic) change of state = no heat echange withh the environment With this option, the program is basedd on very rapid accumulator charging or discharging g processes. In this case, heat echange with the environment is not possible. This option results in large accumulatorr volumes or in smalll V values. Isothermal change of state = complete heat echange with the environment With this option, the program is basedd on very slow accumulator charging or dischargingg processes. In this case, there is complete heat echange with the environment. This results in smaller accumulator volumes, or large V values, comparatively speaking. 6/13

7 2.3. Calculation and input parameters Calculation parameters Input parameters The selected areaa consists of the calculation parameters (p( 2, p 1, p 0, V, V 0 ) as well as the input parameters (T 0, T min and T ma ). The calculation parameters, in red displayed, are the input and output values required r for calculating a hydraulic accumulator. They can be thought of as a mathematical equation that is manipulated according to the desired size. A value cannot be calculated until all other calculation parameters have been entered. The value p 0 is suggested automatically based onn T 0, T ma as well as p 1. If an input value forr p 0 must be specified, i.e. forced by the user, it must be changed manually after the temperature and alsoo after the p 1 have been entered. The following table shows the input and display options for the parameters: Input parameter Input option Abbreviation Description Input value p 2 p 1 p 0 V 0 T 0 T min T ma p 0Tmin p 0Tma p 2 : p 0 V 0 : V 2 Maimumm operating pressuree Minimumm operatingg pressure Pre-charge pressure V Usable volume Effectivee gas volume Gas pre-charge temperature Minimumm operatingg pressure Maimumm operating pressuree Pre-charge pressure at T min Pre-charge pressure at T ma Pressuree ratio Volume ratio Output value (calculation possible) If an input value for p 0 must be specified, i.e. forced by the user, itt must be changed manually after the temperature and also after the p1 have been entered. 7/13

8 For a diagram, see PV graph of an accumulator cycle. This contains all thee parameters of the accumulator calculation. Echange direction in the PV graph 2.4. Number pad & result button The number pad is arranged like the number pad of a calculator. As an alternative to entering the calculation parameters via the keyboard, theyy can also be selected using the mouse/ /touchpad. The result button is also located on the number pad and will w be descrited in the following section. 8/13

9 2.5. Informations and resultss field The label on the result button will change depending on the calculation parameter activated (e.g., p 2 =, p 1 =, V =, V 0 =) ). It is the same as the "equals"" button on a pocket calculator. Activated calculation parameter, in this case "V 0 " Result button, inn this case showing "V 0 ", because calculation parameter "V 0 " has been activated for calculation Results field with "V 0 " at T min and T ma ATTENTION Correct entry of all necessary parameters is required Empty parameters are not valid 9/13

10 After you press the result button, the following information and results fields are displayed on the left and right side. Information field: Pressure ratio Information field: Pre-charge pressure at T min and T ma Information field: Volume ratio Attention, this iss only displayedd when the critical condition is reached. Results field: The label changes according too the calculationn parameter selected. Results field In order to select the calculation parameter to be displayedd for T min and T ma in the results field (in this case V 0Tmin and V 0Tma ), click in the calculationn parameter area Information fields In addition to the actual results field, ASPlight provides important information that suggests an accumulator model (bladder, piston or diaphragm accumulator). p 2 : p 0 = Ma. pressure ratio, in this case p 2 : p 0 = 2.5 : 1 V 0 : V 2 = Volume ratio is only displayed when the critical condition is reached. The critical state is when V 0 : V 2 > 4 : 1 or V 0 : V 2 > 10 : 1. In the eample above, the piston accumulator would w be recommended, depending on the application, diaphragm accumulators could also be used. This must be agreed with HYDAC. p 0Tmin = Hydraulic accumulators must be pressurised with a pre-charge pressure and prior to commissioning (p 0 at T 0 ). These values indicate the pre-charge p 0Tma pressure at minimum or maimum ambient temperature, in this case: p 0Tmin = bar, which means the pre-charge e pressure of the hydraulic accumulator reaches bar at an ambient temperature of 10 C p 0Tma = bar, which means the pre-charge pressuree of the hydraulic accumulator reaches bar at an ambient temperature of 40 C. The pre-charge pressure changes as the operating temperature changes. 10/13

3. Calculation process Calculation in ASPlight is

This section describes the calculation n process: 1.

Define echange speed 4. Define echange direction 5.

Activate desired calculation parameter, here: V 0 7.

Read and evaluate result and information fields

11 3. Calculation process Calculation in ASPlight is similar to using a pocket calculator. This section describes the calculation n process: 1. Select the gas type 2. Define units 3. Define echange speed 4. Define echange direction 5. Enter knownn calculation parameters 6. Activate desired calculation parameter, here: V 0 7. Press result button 8. Read and evaluate result and information fields (default setting is adopted) (p 0 is suggested automatcally by the program based on T and p 1 ) (label can vary according to calculation parameter selected) 11/13

12 4. Eample task Task Accumulator nominal volume = V 0 Solution method V 0 at T min = l V 0 at T ma = l Additional information: p 2 : p 0 = 2.8 : 1 p 0 at T min = bar p 0 at T ma = bar 4.1. Task to calculate V 0 Situation A consumer requires 2.5 litres of hydraulic fluid within a very short time. The minimum pressure must not fall below 180 bar. The pump p charges the accumulator to a maimum of 350 bar. The accumulator is pre-charged at 20 C andd works between 0 C and 60 C. Evaluation Because the pressure ratio is 2.8 : 1, bladder, piston and diaphragmd m accumulators can be used. However, because the V 0 resultt is between and litres, a bladder or piston accumulator is recommended. 12/13

13 4.2. Task to calculate p 1 Situation A 10 litres piston accumulator is discharged within 2 seconds. 1 litre e of hydraulic fluid is discharged. The initial pressure is 1000 bar. The pre-charge pressure is 100 bar at 10 C. Task What is the pressure p 1 when the accumulator is discharged at 0 C and also at 40 C? Solution p 1 at T min = bar p 1 at T ma = bar Additional information: p 2 : p 0 = 10.5 : 1 p 0 at T min p 0 at T ma = bar = bar V 0 : V 2 > 4 : 1 The additional information is used to select the suitable accumulatorr types. E.g., if selected a bladder accumulato or the pressure ratio of o 4 : 1 musst not be eceeded. The piston accumulator ist the t right choice in this eamplee task. 13/13

CALCULATION OF THE ACCUMULATORS 2.2 E 01-12

CALCULATION OF THE ACCUMULATORS 2.2 E 01-12 2.2.1 PRINCIPLE OF OPERATION Gas compression In hydropneumatic accumulators, oil or other liquids are maintained under pressure by a pre-compressed gas, usually