Controls for Industrial Refrigeration Heatpumps · Application: centralized or district heating,...

AC components in IR heat pumps | Anatolii Mikhailov JAN 2013 | 1 Danfoss Automatic Controls

Controls for Industrial Refrigeration Heatpumps

www.danfoss.com/IR


Content Introduction

Types of heatpumps

Refrigerants for Industrial Refrigeration heatpumps

Control systems

Components

Examples



Types of heatpumps


Control systems

Components

Examples


Industrial refrigeration heatpumps - definition

Capacity: more than 100 kW

Temperature ranges: 55’C to 90’C or higher

Refrigerants: all common including CO2, NH3 and hydrocarbons

Application: centralized or district heating, industrial processes

An alternative to other heat sources, such as boilers or electrical heating


Benefits of IR heatpumps

Energy saving

Operational cost reduction

COP depends a lot on application, temperature range, uptime etc.

Typically COP would be between 3 and 8, the higher number is for add-on heat pumps

ROI is the main consideration selecting IR heatpumps, as other common alternatives (such a boiler) available


IR heatpumps technologies

IR HP

NH3 - medium

temp

NH3 – high temp

Hydrocarbons

HFC CO2

Absorption

Hybrid



Types of heatpumps


Control systems

Components

Examples


Groups of Industrial Refrigeration Heatpumps

Dedicated heat pumps

built mainly for heating

Reusing high potential heat from refrigeration system

“add-on” to the refrigeration system (additional high stage compressors)

Heat reclaim

Reclaim of the heat on a “normal” condensation level


Different control and components requirements for different groups

Temperature control (refrigerant side/media side)

Pressure/temperature envelope

Efficiency optimization



Types of heatpumps


Control systems

Components

Examples


Refrigerants for Industrial Refrigeration Heat Pumps

NH3 – wide range of applications; oil temperature could be a limitation

CO2 – good for high temperature differences, not so for small ones (limited choice of big capacity compressors)

HFC – high GWP, in general lower efficiency than e.g. NH3, considered as “safety refrigerants”

Hydrocarbons – big charge, only special applications (chemical/petrochemical); very high temperatures could be reached

http://portal.danfoss.net/RA/SU/RAMarketing/MarketIntelligence/GreenDriver/Ref/HC/Pages/default.aspx


NH3 heat pumps

Condensing – most efficient at relatively small temperature lift

900C corresponds to ca. 51 bar (60-65 bar MWP required)

780C corresponds to ca. 40 bar

Media and capacity control

Applications with pressures above 50 bar are still rare


CO2 heat pumps

Gas cooling – variable temperature; most efficient at high temperature lift and low inlet water temperature

High pressure side up to 140 bar

Low pressure side 40 to 90 bar

High pressure control on refrigeration side is crucial for COP


CO2 and NH3 comparison (schematic)

It is necessary to condense ammonia at around 900C to get high temperature water at 900C

CO2 could be condensed (or cooled) at much lower temperatures – but only if a sufficient water temperature difference is available

CO2 NH3

Water

Pinch point

Exchanged heat

Tem

pera

ture



Types of heatpumps


Control systems

Components

Examples


NH3 heat pumps key control areas

Capacity of heat pump compressors controlled by heated media temperature

For add-on heat pumps intermediate temperature is given by the condensing temperature and variable

For stand alone intermediate temperature is selected to maximize COP

Suction regulators are needed for high pressure side (start up / stand still control to avoid condensation)

Frequency control of compressors is an advantage to balance the load

High stage might be low charge – should be taken in to account in control algorythms


CO2 heat pumps key control areas

CO2 heat pumps are always transcritical

High pressure control is needed

Frequency control of compressors is an advantage to balance the load

Typically heating is split in sevral stages / heat exchanges to maximize COP



Types of heatpumps


Control systems

Components

Examples


Operation envelope consideration

NH3: high pressure and high temperature combination

pressures up to 50 bar or higher

Discharge temperatures above +1000C

CO2: extremely high pressures (up 140 bar)


Components selection consideration

Max working temperature – taking discharge temperature into account

Max working pressure

Differential pressure – both for CO2 and NH3

Material compatibility – high pressure / temperature refrigerants might have different influence on elastomers

Control requirements for control valves and sensors


Danfoss components range Component groups CO2 NH3

Line components and filters high pressure

- All 52 bar, special version for 65 bar

Line components and filters low pressure

All 52 bar

All 52 bar

Control valves high pressure

ICMTS, CCMT up to 140 bar

ICS and ICM (special sealings),

up to 65 bar

Control valves low pressure

CCM, 90 bar

ICS and ICM, up to 65 bar; AKVH 90

bar

ICS, ICM – up to 65 bar, ICF – 52 bar


Content Types of heatpumps


Control systems

Components

Examples


Case story: ewz, heat pump provider Wettstein (Switzerland)

pictures courtesy of ewz and Wettstein


Case story: Wettstein (Switzerland)

Purpose: central heating and cooling

Refrigerant: NH3

Temperature levels:

+65/+700C

+26/+300C

+6,8/+40C

Pressure rating: 50/24/16 bar

2 stage compression

Suction pressure regulators, float valves and motorized valves (ICM) for capacity control


Case story: Advansor (Denmark)


Case story: Advansor (Denmark) Purpose: central heating

Electricity from windmills

Refrigerant: CO2

Capacity: 980 kW

Pressure rating: 120/90 bar

waste water as a source (cooled from 20 to 100C that is returned to the sea)

water heated from 35 to 800C

ICMTS valves for high pressure regulation


Questions?


Back-up slides

AC components in IR heat pumps | Anatolii Mikhailov JAN 2013 | 29 Danfoss Automatic Controls February 13 / 29

ICV Reliability and performance

52 bar is standard MWP

V-port regulation cone as standard

Reliable operation

Designed for Industrial Refrigeration

Ready for the refrigerants of tomorrow, today

Compact and low weight design

High MOPD

Corrosion protected with Chrome Zinc


ICF A range of combinations

30

ICF 25-40

valve housing

ICFF ; Filter

ICFC; Check valve

ICFR; Regulating valve

ICFS25; Stop valve

ICFB; Blank cover

ICFW; Welding module

ICM; Motor valve ICFE; Solenoid valve

ICFN; Stop/check valve


ICMTS – technical features

Designed for high pressure CO2 systems. applications for a maximum working pressure of 140 bar / 2030 psig.

Applicable to other common refrigerants as well. The ICMTS is not applicable for flammable refrigerants.

Direct coupled connections.

Connection types are DIN butt weld. (Solder)

Low temperature steel body.

Low weight and compact design.

Regulating cone ensures optimum regulating accuracy particularly at part load.

Manual opening possible via ICAD or Multi-function tool.

PTFE seat provides excellent valve tightness.

Magnet coupling - real hermetic sealing.


CCM - Gas Bypass & Liquid Expansion Valves for CO2

Designed to allow for intrinsic standstill security of CO2 refrigeration systems: MWP 90 bar (1305 psi).

Balanced and stabilized cone design to allow for MOPD of up to 50 bar (725psi).

Combined DIN butt weld and solder connections.

Stainless steel housing for high strength and corrosion resistance.

Designed for both use in gas bypass and expansion applications.

Available in four capacity steps with Kv: 0.6 – 4.2 (Cv: 0.7 – 4.8).


Dimension: DN 6 - DN 300

Pressure: PS 40 bar (PS 50-52 –heatpumps only up to DN 200)

Connection: DIN, ANSI,SOC, NPT

Types: Cap / Handwheel Angel / Straight

Material: Steel or stainless steel

Approvals: PED, CRN, DNV, BV

Stop Valves: SVA + SNV

Controls for Industrial Refrigeration Heatpumps · Application: centralized or district heating,...

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