Heat pump boiler and control method for the same

Abstract

Disclosed are a heat pump boiler and a control method for the same. The heat pump boiler includes an outdoor unit having an outdoor-unit heat-exchanger, a water pipe including a water-feed pipe and a water-return pipe connected to the outdoor unit to feed water to the outdoor unit or to return low-temperature or medium-temperature water produced in the outdoor unit to an external location, heat exchangers connected to the water pipe to produce medium-temperature or high-temperature water, a variable-capacity compressor connected to the heat exchangers, a buffer tank connected to the water pipe, and an externally-wound heat exchanger to collect waste heat radiated from the compressor. A temperature of water stored in the buffer tank is raised using the collected waste heat, and, during a defrosting operation, the water stored in the buffer tank is fed to the outdoor-unit heat-exchanger to defrost an evaporator of the outdoor unit.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of Korean Patent Application No. 10-2011-0056083, filed on Jun. 10, 2011 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.BACKGROUND[0002]1. Field[0003]Embodiments of the present invention relate to a heat pump boiler and a control method for the heat pump boiler.[0004]2. Description of the Related Art[0005]Recently, boiler products using a high-efficiency electric heat pump that exhibits superior energy efficiency than conventional combustion boilers have been actively studied and developed.[0006]Single-stage cycle types using a single refrigerant employ R410A or R407C refrigerant, and are respectively used within a maximum temperature of water of 55° C. or 65° C. in terms of properties of refrigerant and cycle components.[0007]A house having high thermal-insulation efficiency may be sufficiently heated even at the maximum temperature of water acqu...

AI Technical Summary

Benefits of technology

The present invention provides a heat pump boiler with an outdoor unit that has an outdoor-unit heat-exchanger for heat exchange between refrigerant and water, and a water pipe connected to the outdoor unit for direct water production. The boiler also includes a compressor with a variable capacity to produce hot water at different temperatures, and a buffer tank for storing hot water for defrosting the outdoor unit. The heat pump boiler allows for efficient production of hot water and prevents discharge of cold water, and also provides a control method for the heat pump boiler.

Problems solved by technology

However, existing houses exhibit insufficient heating effects under a low temperature of water because of low thermal-insulation efficiency thereof and provision of a low-efficiency radiator (or fan coil unit).

The reason for using the two-stage cycles is that when a compressor compresses a single refrigerant from a low evaporator pressure, which corresponds to a low temperature of outside air, to a high condenser pressure which corresponds to a high water temperature, an excessive compression ratio occurs.

Thus causes a significant deterioration in the reliability and volumetric efficiency of the compressor, which may make it difficult to construct a high-efficiency system.

However, the two-stage cycles are very unfavorable for energy efficiency because it may be necessary for the refrigerant to pass through both the two-stage cycles even when preparing water of a medium-, or low- temperature other than water of a high temperature.

In this case, however, since all of the three plate-shaped heat exchangers are mounted to a high-temperature water preparation unit and the high-temperature water preparation unit is in turn connected to an outdoor unit via a refrigerant pipe, installation of a heat pump boiler may require refrigeration and electrical engineers, which increases installation cost and time.

Most heat pumps perform a defrosting operation by switching a refrigerant cycle for a moment from the outdoor-unit heat-exchanger to a condenser before heating performance thereof is considerably deteriorated due to frost excessively formed on a surface of the heat exchanger.

Thus, the temperature of heating water is lowered during the defrosting operation, and an additional heating operation may be inefficiently performed after completion of the defrosting operation to repeatedly raise the temperature of water.

Images