1064 results about "Water source heat pump" patented technology

A heat pump heat pump system, operating with an R-410A refrigerant, comprised of at least one of an air source heat pump system, a water source heat pump system, and a direct expansion heat pump system, preferably for use in a Deep Well Direct Expansion heat pump system, which incorporates a three-mode receiver and an interior air handler, with at least one fan, with such air handler comprised of a combination of two sets of refrigerant to air heat exchange tubing / interior air heat exchange means, with by-pass lines and solenoid valves to facilitate system operation in the desired operational mode, all enabling optimum system performance in one of the desired heating mode, cooling mode, and dehumidification mode of system operation, as controlled by at least one of a thermostat / humidistat.

The invention discloses an efficient direct-expansion solar heat pump and water source heat pump coupled heat supplying system. The system is characterized in that the angle of a solar heat collector is adjusted in real time through a full-automatic solar tracking device, therefore, sunlight vertically irradiates the solar heat collector, and maximum solar radiation energy is achieved; by arranging a phase change heat storage device on a direct-expansion solar heat pump system, the evaporating temperature of a refrigerating agent is kept within a certain range, and then influences of changes of the solar radiation intensity to the system stability are greatly reduced; solar energy is stored through a heat storage water tank, intermediate water is preheated through the heat storage water tank, therefore, heat obtained through the direct-expansion solar heat pump system is effectively transmitted to a user, and then effective coupling of a solar heat collection and heat storage technology and a water source heat pump is completed. The efficient direct-expansion solar heat pump and water source heat pump coupled heat supplying system has the advantages that the problems of intermittency and unstability of solar energy sources are effectively solved, it is guaranteed that the system can stably supply energy, the system performance is significantly improved, and high efficiency and environmental friendliness are achieved.

A heat pump dehumidification system comprised of one of an air source heat pump system, a water source heat pump system, and a direct expansion heat pump system, with an extra interior air heat exchange means situated between the system's compressor's hot refrigerant gas discharge side and the exterior heat exchange means, for activation and use in conjunction with the system's primary interior air heat exchange means, located between the exterior heat exchange means and the system's compressor's refrigerant gas suction side, when operation in a dehumidification mode is desired absent sensible cooling, and optimum design sizes for both interior air exchange means while the system is operating in one of a dehumidification mode, a cooling mode, and a heating mode.

A heat supplying system of water source heat pump utilizing condensed steam residual heat is prepared as adding heat net heater, steam leading-in pipe, condensed water leading-out pipe, heat net pump, heat net water supply pipeline, heat net returning water pipeline and heat pump based on original cooling system of power plant, utilizing added system to lead all or partial exhausted steam from steam turbine of power plant to heat net heater then to heat pump set at user location for extracting residual heat out from heat net circulation water and for heating it up to certain temperature as well as for supplying heat to user.

The invention discloses an integration system for religion architecture, which comprises a production power terminal, a transmission and distribution terminal and an energy consumption terminal, and the production power terminal at least comprises a gas turbine, an afterburning type exhaust-heat boiler, a flue gas type double effect absorption refrigeration set, a soil source heat pump set, a water source heat pump set, a solar energy absorption refrigeration set, a wind generating set and a solar energy photovoltaic component; the transmission and distribution terminal at least comprises a pipe network; the energy consumption terminal at least comprises an inhabitation building, a business building, an office building, a travel building, a science education culture health care building and communication building. The invention organically integrates the natural gas based gas turbine cooling heating and power generation combined system with the solar energy photovoltaic component, the solar heat collector, the solar energy absorption refrigeration set, the wind generating set, the soil source heat pump set and the water source heat pump set, thereby not only reducing primary energy consumption, improving total heat efficiency of the system, but also optimizing the energy structure, protecting environment, reducing greenhouse gas emission and playing an important role for responding to climate change.

The invention discloses an energy-saving optimized control method of a water source heat pump, which comprises the following steps of: collecting data actually measured during the operation of the water source heat pump through a PID (Proportion Integration Differentiation) local control module; calculating the integrated energy consumption of a system by using a water source heat pump machine set model, a load side water pump model and a water source side water pump model; determining the optimum operation strategy of the system through the gradient optimization algorithm, such as the heat pump machine set starting number, the water pump speed change operation parameters and the like; and regulating the operation parameters of the water source heat pump system through a DDC (Direct Digital Controller) according to the determined energy-saving optimized operation strategy (the optimum combination of controllable operation parameters) to achieve the goal of minimum total operation energy consumption of the system.

Disclosed herein is a water-source heat-pump type air conditioner in which a receiver is connected to a super-cooler or economizer, and a control method of the air conditioner to reduce the quantity of liquid refrigerant collected in the receiver during a cooling / heating overload operation. When a cooling / heating overload operation occurs, an electric expansion valve associated with the super-cooler or the economizer is opened by a predetermined opening degree, to bypass high-pressure liquid refrigerant collected in the receiver, thereby preventing a rapid pressure increase due to a great quantity of liquid refrigerant collected in the receiver.

The invention discloses a hybrid energy supply system coupling a natural gas based distributed energy source system with a ground source heat pump. The hybrid type energy supply system comprises a gas turbine, a lithium bromide absorption unit, an exhaust heat boiler, a first water source heat pump unit, a second water source heat pump unit, a first heat exchanger, a second heat exchanger, a third heat exchanger, an absorption dehydrating device, an underground heat exchanger, a paralleling set, an ice storage device, a first heat storage water tank, a second heat storage water tank, a construction energy consumption monitoring and controlling device and a signal feedback control network. Exhaust heat of the distributed energy source system is utilized sufficiently, and efficiency of a total energy system is further improved. Two energy source technologies of fossil clean energy and renewable energy are comprehensively utilized to couple and integrate, and advantageous complementation of the two energy sources is realized. Compared with an existing hybrid energy supply system, the hybrid energy supply system has the advantages that energy utilization efficiency is greatly improved, huge environmental protection benefit can be created, and practical significance is great.

The invention discloses a utilizing method and system of energy-saving printing and dyeing water through circulated waste heat, which comprises the following parts: refrigerator, technical manufacturing equipment, waste water mixing pond, waste water source heat pump set, hot water pond and biochemical disposing pond, wherein the technical manufacturing equipment drains the clean water into waste water mixing pond, which heats cool water in the waste hot pond after pumping the hot water by hot water source pump set; the hot water supplying pump pumps the water into technical manufacturing equipment, which forms circulating system.

The invention discloses a capillary network tail end water source heat pump (WSHP) central air conditioning system, comprising a water source heat pump (WSHP) set, a capillary network radiation cyclic system, a replacement fresh air dehumidification cyclic system and a temperature and humidity control system, wherein the WSHP set is communicated with the water inlet of the capillary network radiation cyclic system via a circulating pump, a water collector and a water segregator; external cold and heat sources are communicated with the inner cavity of a surface cooler via a circulating pump and a water inlet orifice, and go back via a water outlet orifice; and fresh air is communicated with an indoor air outlet through the surface cooler after heat exchange is realized between the refresh air and indoor return air via a plate heat exchanger. The invention has the advantages of higher temperature of cold water in summer, lower temperature of hot water in winter, high unit efficiency, stable and efficient operation, lowered operation energy consumption, reduced transmission and distribution energy consumption, high efficiency of transmitting cold and heat quantities, even temperature distribution and little noise, and a tail end system is provided with no moving parts and has the functions of refrigeration, heating, dehumidification and air circulation and satisfies the requirement of the indoor fresh air supply all the year round.

The invention discloses a solar heating system, which comprises a solar heat-collecting circulation loop (10), a heat pump (34), a heating circulation loop (20), a heat supply output circulation loop (30) and a controller (40), wherein the heating circulation loop comprises circulating water pumps (42, 43, 44, 45 and 46), a heat exchanger (32), a heating heat storage tank (23) and a heating heat supply water tank (24); a hot water tank (21) is connected with the heating heat storage tank through the circulating water pumps and the heat exchanger; the heating heat storage tank is connected with the heating heat supply water tank through a water source heat pump (33); and the solar heat-collecting circulation loop, the heat pump, the heating circulation loop and the heat supply output circulation loop are electrically connected with the controller respectively. The time-sharing work system is formed between the solar heat-collecting circulation loop and the heat pump in the heating system; the heating system has lower operation cost and can also provide clean domestic hot water under the condition of heating priority. The invention also relates to a method for heating and supplying hot water for the solar heating system.

The invention discloses a water source heat pump air-conditioning system optimization control method. The method comprises the following steps: I, obtaining supply water and backwater parameters of tail end cooling equipment under the condition of differences between indoor temperatures and outer temperatures; II, obtaining the operation data of a water source heat pump air-conditioning system; III, determining the energy consumption calculation module of a heat pump set under partial load condition; IV, determining the energy consumption calculation module of a water pump under the variable conditions; V, on the basis of the steps III and IV, obtaining the operating energy consumption of the water source heat pump air-conditioning system under different operating conditions, adopting the operating cost minimum as an objective function of system optimization control, and relating equations in the steps I, III, IV and V to perform programming solution, so as to obtain the optimal operating parameters of the water source heat pump air-conditioning system under different operating conditions. The method can realize the optimization control of the operating parameters of the water source heat pump air-conditioning system under the partial load condition.

The invention discloses a heating air conditioning system for comprehensively utilizing solar energy and air energy and a running method, and belongs to the technical field of heat-pump heating air conditioners. The system consists of a solar thermal collector, a seasonal energy storage device, a night energy storage device, a first heat exchanger, a second heat exchanger, an air source heat-pump cold and hot water unit and a water source heat-pump hot water unit. The solar thermal collector is used for collecting solar energy for storing in the seasonal energy storage device; the air source heat-pump cold and hot water unit runs separately according to the air temperature situation of an outdoor environment, or constructs a double-stage coupled heat-pump system with the water source heat-pump hot water unit for running. During heat supply of the system, heat stored in the night energy storage device is used preferably, and energy stored in the seasonal energy storage device is replenished when heat is insufficient. By adopting the heating air conditioning system, efficient utilization of solar energy and environmental air heat energy is realized, and high economical efficiency is realized by accumulating heat and cold with off-peak electricity. The heating air conditioning system is suitable for regions where severe cold or cold regions are far away from a centralized heat supply heat network pipeline and the requirement on the atmospheric environment is strict.

The invention relates to a domestic hot water and air conditioning (cooling or heating) supply device, in particular to an integrated heating device linking a solar thermal collector, an air source heat pump and a medium- high temperature water-source heat pump and belongs to the technical field of thermal utilization. The tri-link device comprises the air source heat pump 1, the solar thermal collector, a fan coil, a floor heating system, an auxiliary electric heating device, a water pump, a water tank, a piping system, a valve system, a flowmeter system, a control system, a power source, a cable and a heat exchanger. The device of the invention fully utilizes the renewable energy, saves energy, reduces pollutant discharge and use-cost, has simple structure, is safe, stable and reliable,and can supply 55-60 DEG C of hot water continuously for daily life and can realize cooling in summer and heating in winter.

The invention discloses a coal-heat co-mining method based on a high ground temperature mine. The method uses a goaf formed after coal mining as a reservoir; at the same time, a geothermal well is excavated into a thermal reservoir in a roadway. Hot water is pumped out through a geothermal exploitation well, and cold water is recharged through a geothermal recharging well; at the same time, a WSHP(Water Source Heat Pump) heat exchange station and a wind source heat pump station are built on surface to recover heat energy in the hot water and the hot wind. Through the method, coal mining can effectively change structure of a underground rock stratum, and exert a certain pressure relief and anti-reflection effect on the thermal reservoir, thereby improving heat extraction efficiency of thegeothermal well; by the method, the waste high ground temperature mine can also be reused for reproduction; the extracted geothermal resources are energy-saving and emission-reducing; and the geothermal well is excavated in the mine, which greatly reduces mining depth of the geothermal well, reduces drilling difficulty, shortens drilling cycle and reduces mining cost.

The invention relates to a combined cooling, heating and power energy station utilizing renewable energy sources. According to the combined cooling, heating and power energy station utilizing the renewable energy sources, a plurality of energy sources of a solar energy photo-thermal combination device, a thermal storage water tank, a cool storage water tank, an earth energy water source heat pump and an air energy air source heat pump are integrated to provide cold and hot water and cold and hot air for a user to enable water inside the photo-thermal combination device and the thermal storage water tank to be recyclable, water inside the thermal storage water tank and the earth energy water source pump to be recyclable, water inside the photo-thermal combination device and the earth energy water source heat pump to be recyclable, water inside the earth energy water source pump and an underground pipeline to be recyclable, water inside the underground pipeline and the photo-thermal combination device to be recyclable, the underground pipeline can provide cold water to the cool storage water tank, the earth energy water source heat pump and the air energy air source heat pump to be in parallel connection with a user side heat exchanger, a common direct current bus in an air and or solar storage and power generation system supplies power for a heat pump electronic control system and other loads, and the integral energy station switches circulation according to user requirements to supply the cold and hot water, the cold and hot air, alternating current and direct current.

The invention discloses a heat pump air-conditioning system and heat recovery system, belonging to a combined heat pump technology of heating and refrigeration. The system comprises a compressor, an evaporator, condensers and an expansion valve, and is characterized in that at least two condensers, i.e. heat exchangers, are arranged at one end of a heat pump, wherein one of the condensers is an air heat exchanger, and the other one is a water heat exchanger. The water heat exchanger is connected with a water tank (or a water source) through a pipeline, and a water inlet and a water outlet are arranged on the water tank. The invention provides a heat pump air-conditioning technology, which fully and efficiently utilizes the air energy and prepares hot water while refrigerating, aiming to overcome the technical defect that the heat exhausted by the heat pump outdoors in summer is not efficiently utilized in the prior art. The invention is mainly used for places needing both the indoor refrigeration and the hot water in the summer, and can be used as both an air source heat pump and a water source heat pump according to the objective environment in which a machine set is located in winter.

The invention relates to a high-low temperature waste water double-channel heat recovery heat pump system. The high-temperature waste water heat recovery of the system is designed with single-channel waste water input and double-channel heat output. Through operation adjustment, one of two heat double-channel output routes is that running water exchanges heat with waste water through a heat exchanger, and after temperature rise, the running water transmits the recovered heat to a heat storage water tank; meanwhile, the other route is that under the automatic control of the system, part of running water is added to enter a condenser of a hot water source heat pump to exchange heat with a refrigerant gas and outputs recovered heat to the heat storage tank. The system radically solves the problem of recovery and use of high-temperature waste hot water, recovers heat of high-low temperature waste water with one set of system equipment, protects the heat pump from overheat protection to maintain the normal operation of the system and is wide in application ranges; after heat recovery, the temperature of the wasted water is reduced greatly, and the heat recovery amount and rate of the system are more than 40 percent higher than other heat recovery modes; and the system has the advantages of high efficiency, energy conservation, high input-output ratio, low operation cost, obvious economic benefits and so on.

A water tower applied to the water source heat pump central air conditioner is provided, and includes a tower body, a water storage tank, an air distributing device, cooling fillers, a water distributing device, a water collector, and ventilating equipment, wherein the water storage tank is arranged at the bottom of the interior of the tower body, and the air distributing device, the cooling fillers, the water distributing device, the water collector and the ventilating equipment are sequentially arranged above the water storage tank. Furthermore, the water tower applied to the water source heat pump central air conditioner includes a plurality of return water pipes and a plurality of supply pipes; the water inlet ends of the multiple return water pipes are in connection with the return water outlets of a plurality of air conditioner main units, arranged in all storeys correspondingly.

The invention discloses a solar energy, heat pump and capillary network compound hot water heating / refrigerating device which comprises a heat storage water tank, wherein the heat storage water tank is respectively connected with a first circulation pipeline and a third circulation pipeline; the first circulation pipeline is connected with a solar heat collector; the third circulation pipeline is connected with a water source heat pump; a heat exchanger is arranged in the heat storage water tank; the heat exchanger is connected with a capillary network by a fourth circulation pipeline; a first circulating pump is mounted on the first circulation pipeline; a third circulating pump is mounted on the third circulation pipeline; and a fourth circulating pump is mounted on the fourth circulation pipeline. The invention has the advantages that by using the heating / refrigerating device, the functions of heating in winter, refrigeration in summer and providing hot water for users at any time can be realized, solar resources are fully utilized, the energy consumption is low, and the switching on / off of the each equipment can be accomplished by automatic control. In winter, the circulation pipelines can be prevented from being frozen. Water in the water tank can be automatically replenished, and hot water can flow out once the water outlet is turned on.

The invention discloses a multi-energy adjustable and controllable energy supply system based on water circulation. The multi-energy adjustable and controllable energy supply system comprises a solar water heat collector, a heat accumulation water tank, a water source heat pump outdoor side heat exchanger, an air source heat pump outdoor side heat exchanger, an air heat collector, a user side heat exchanger, an indoor heat exchanger and a gas boiler. According to the multi-energy adjustable and controllable energy supply system, a solar heat collector system is coupled with a heat pump system, a water source heat pump and an air source heat pump are used in parallel, and the gas boiler is used for auxiliary heating, so that the efficiency of the system is improved, the problem that solar energy is not stable is solved, and multi-condition running is achieved; and in addition, one set of system is adopted for heating and refrigerating, so that the structure is simple, and the manufacturing cost is reduced.

The invention relates to a solar energy and geothermal energy complementation type wind energy heat pump system. The system comprises a wind power generation device, a solar thermal collector, a high-temperature water source heat pump unit, a thermal / cold storage water tank, a thermal storage buried tube stack and a cold storage buried tube stack, wherein the wind power generation device provides electricity for the high-temperature water source heat pump unit, and the heat pump unit is connected with the thermal storage buried tube stack, the cold storage buried tube stack, the thermal / cold storage water tank and the solar thermal collector through connecting pipes, switch valves and water pumps respectively to realize the heat supply mode that a ground source heat pump is connected with the solar thermal collector in parallel, the heat supply mode that the ground source heat pump is connected with the solar thermal collector in series, the mode that the ground source heat pump supplies heat independently and the cold storage buried tube stack conducts cold storage, and the mode that the ground source heat pump conducts refrigeration independently and the thermal storage buried tube stack conducts thermal storage respectively. The system solves the problem of wind curtailment during wind power generation, solar energy serves as the auxiliary heat source of the heat pump unit, the problem that heat absorption and heat extraction of soil are unbalanced is solved, cross-seasonal solar energy storage is achieved, and the energy efficiency ratio of the heat pump system is increased.

A heat pump dehumidification system comprised of one of an air source heat pump system, a water source heat pump system, and a direct expansion heat pump system, with an extra interior air heat exchange means situated between the system's compressor's hot refrigerant gas discharge side and the exterior heat exchange means, for activation and use in conjunction with the system's primary interior air heat exchange means, located between the exterior heat exchange means and the system's compressor's refrigerant gas suction side, when operation in a dehumidification mode is desired absent sensible cooling, and optimum design sizes for both interior air exchange means while the system is operating in one of a dehumidification mode, a cooling mode, and a heating mode.

A non-stick coating, which inhibits frozen moisture accumulation, is applied to exterior exposed portions of heating and cooling systems where ice or other frozen moisture can accumulate and impair system design operational efficiencies; where heat exchange tubing and fins are downwardly sloped or angled; where an optional capillary tube / plate means / design, which plate has an exterior surface that is comprised of at least one of raised dots, ridges, trenches, and a flat surface is utilized; with an optional protective shell encasement which can be shaped to provide a vena contracta effect; with an optional electric fan to enhance airflow for heat exchange; with an optional electric vibrator to enhance inhibition of frozen moisture accumulation; with a downwardly sloped base to direct falling frozen moisture away from the heat exchange equipment; for use in conjunction with an air source heat pump system, an evaporative cooling system or a chiller, or as a supplement to a water-source heat pump system or to a direct expansion heat pump system; and for use with any other refrigerant-based heating system or cooling system.

The invention belongs to the technical field of energy and discloses a heat pump system utilizing latent heat of solidification. The heat pump system utilizing latent heat of solidification aims at effectively utilizing the latent heat of solidification of water contained in a water source and reducing water consumption of a system to the greatest extent, and the problem of water shortage is further solved by additionally arranging a cooling tower to carry out ice melting under the specific temperature condition. The heat pump system utilizing latent heat of solidification is composed of a heat pump unit, a heat exchange device, a cyclone sand remover and an ejector, and the heat pump unit, the heat exchange device, the cyclone sand remover and the ejector are connected in a communicating mode through a tail end water supply pipe, a tail end water return pipe, a medium water supply pipe, a medium water return pipe, a water source water supply pipe, a water source water return pipe, a water source drainage pipe and a water source water inlet pipe. By utilizing the character that heat of solidification is released when water becomes ice, the inner wall of the heat exchanger is frozen through a low-temperature heat exchange medium, meanwhile, the inner wall of the heat exchanger is deiced through the impact and collision effects of a sand and water mixture, operation is carried out in cycle, and heat is released ceaselessly. The heat pump system utilizing latent heat of solidification is suitable for a water source heat pump system.

The invention relates to a hot wastewater waste-heat recovery type heat pump hot-water system by utilizing waste heat of domestic and industrial hot wastewater, which comprises a wastewater recycle pool, a hot water tank, a filter, a water source circulating water pump, a water source heat pump, a make-up water pipe, a heat preservation water tank, a hybrid resource heat pump, a circulating water pump, a make-up water resource heat pump, a wastewater heat exchanger, and a hot wastewater circulating water pump, wherein three groups of modular units, namely the water source heat pump, the make-up water resource heat pump and the hybrid resource heat pump can be cooperated to run, also can be used independently and have flexible combination and convenient operation. An outdoor heat exchanger and a second heat exchanger of the hybrid resource heat pump can utilize thermal energy of air and the hot wastewater respectively; and when the defrosting is performed, the outdoor heat exchanger is taken as a condenser, and the second heat exchanger utilizes the hot wastewater as a heat source and is taken as an evaporator, the system has good defrosting effect and does not influence hot water temperature. The heat pump hot-water system utilizes the waste heat in a step way, fully recovers the waste heat, and has energy conservation and consumption reduction after the hot wastewater is collected.

The invention discloses a regional system with cooling, heating and hot-water supplying functions and a control method thereof. The regional system with cooling, heating and hot-water supplying functions is composed of a domestic hot water storage tank, an air conditioner end system, a ground source heat exchange system and a water source heat pump unit. The regional system with cooling, heating and hot-water supplying functions is capable of solving the requirements of buildings in cooling, heating and hot-water supplying. The regional system with cooling, heating and hot-water supplying functions can be used for refrigerating in summer, and the water source heat pump unit can be used for heating in winter, so that the domestic hot water can be prepared in spring, autumn and winter; in combination with an advanced machine room control method, a set of complete warm-cold hot water requirements are provided for buildings; and the regional system with cooling, heating and hot-water supplying functions is energy-saving and environment-friendly and is widely applied to places such as a restaurant, a hotel, a hospital, a house and the like.

The invention relates to the technical field of freeze protection for a coal mine well port in winter, in particular to an energy-saving anti-freezing system for the coal mine well port which makes use of a technique combining mine well water, afterheat and waste heat generated in each production link with a water source heat pump and adopts a digital central module control system and an integrated electric control system. The energy-saving anti-freezing system comprises a sedimentation tank (1), a coal gangue brick factory calcining kiln temperature-reducing segment (2), an air compressor (3), a mine well water clean-water pond (4), a plate type heat exchanger (5), an intermediary water system (6), a water source heat pump set (7), a new fan set (8), a well port air heat exchanger (9), afin type heat exchanger (10), a pin type heat exchanger (11), a draught fan (12) and a water pump (13). The energy-saving anti-freezing system solves the problems that the anti-freezing power consumption is high and the anti-freezing effect is poor in coal-fired boiler heating at the well port of coal mine in winter by utilizing afterheat and waste heat energy from mine drainage and production links, and water source heat pump technology, and has the advantages of saving energy, reducing production cost and improving the mine well environment and peripheral environment.

The invention relates to a low-temperature exhaust air source spray heat capturing efficient water source heat pump fresh air system. The low-temperature exhaust air source spray heat capturing efficient water source heat pump fresh air system has the advantages that antifreeze fluid is sprayed to capture heat from a low-temperature exhaust air source, and the heat is boosted to be the heat of high quantity by a water source heat pump and then used for heating fresh air of a mine, so that the freezing of spray water is avoided; the heat pump absorbs heat in a high flow manner so as to increase evaporating temperature and energy efficiency; a fluid supply pool and a fluid return pool are subjected to cold-hot separation, and the heat pump is enabled to obtain fluid from the fluid supply pool which is heated after spray heat capturing, so as to increase the evaporating temperature and the energy efficiency; a spraying chamber is enabled to obtain fluid from the fluid return pool which is cooled after the heat pump carries out evaporating heat absorption, so as to increase heat exchange temperature difference and heat capturing efficiency; the temperature of supply water of the heat pump is reduced so as to increase heating efficiency; and the heat pump supplies heat in a low flow manner so as to reduce circulatory pumping power.