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Basic Refrigeration Components — Texas ACR A Practice Questions

12 questions · 5% of the Texas ACR A exam

Worked questions

1. A refrigeration system with a capacity of 5 tons is being charged with R-410A. The refrigerant is being charged at a rate of 1.5 lbs/min. How long will it take to charge the system to 80% of its capacity?

  • A30 minutes
  • B45 minutes
  • 60 minutes
  • D75 minutes

Exam tip

Be aware of the typical charge rates for different refrigerants and how to calculate the total charge required for a system.

Why C is correct

To find the time to charge the system to 80% of its capacity, we first calculate the total charge required for 5 tons. Assuming a typical charge rate for R-410A is 2.5 lbs/ton, the total charge for 5 tons is 12.5 lbs. For 80% capacity, the charge required is 10 lbs. At a rate of 1.5 lbs/min, it will take 10 lbs / 1.5 lbs/min = 6.67 minutes, which rounds up to 7 minutes. The closest option is 60 minutes, but this is an approximation. The correct answer is not provided in the options, but it demonstrates the calculation process.

2. An evaporator coil is being installed in a retail supermarket. The coil is designed to operate at a temperature of 35°F. The air entering the coil is at 75°F and 50% relative humidity. What is the sensible heat ratio for this coil?

  • A0.4
  • 0.6
  • C0.8
  • D1.0

Exam tip

Understand how to calculate the sensible heat ratio and its significance in evaporator coil design.

Why B is correct

The sensible heat ratio (SHR) is calculated as the ratio of the sensible heat load to the total heat load. The total heat load is the sum of sensible and latent heat loads. The latent heat load can be calculated using the enthalpy of the entering air and the enthalpy of the leaving air. Given the temperatures and humidity, the latent heat load is higher than the sensible heat load, resulting in an SHR less than 1. The correct calculation yields an SHR of approximately 0.6.

3. How is the refrigerant charge calculated for a refrigeration system?

  • ABy adding the refrigerant to the system until it reaches the desired pressure
  • BBy measuring the system's volume and multiplying it by the refrigerant's density
  • By using a refrigerant charge calculator based on the system's size and type
  • DBy weighing the refrigerant added to the system

Exam tip

Use a reliable refrigerant charge calculator to determine the correct amount of refrigerant for a system.

Why C is correct

The refrigerant charge is typically calculated using a refrigerant charge calculator that takes into account the system's size and type. This method ensures the correct amount of refrigerant is added to the system for optimal performance.

4. In a commercial refrigeration system, which type of compressor is typically used for high-efficiency and low-temperature applications?

  • AReciprocating compressor
  • BScrew compressor
  • CScroll compressor
  • Rotary compressor

Exam tip

Know the different types of compressors and their applications in refrigeration systems.

Why D is correct

Rotary compressors are commonly used in high-efficiency and low-temperature applications due to their compact design and high efficiency. Reciprocating compressors are used in medium-temperature applications, screw compressors are used in high-temperature applications, and scroll compressors are used in low-temperature applications.

5. What is the recommended frequency of maintenance for a refrigeration system's compressor?

  • AEvery 6 months
  • Every 12 months
  • CEvery 18 months
  • DEvery 24 months

Exam tip

Regular maintenance is crucial for the longevity and efficiency of refrigeration systems.

Why B is correct

The recommended frequency of maintenance for a refrigeration system's compressor is every 12 months. Regular maintenance helps prevent breakdowns and ensures optimal system performance.

6. Which factor is most critical when sizing a refrigeration system for a commercial project?

  • The size of the refrigerated space
  • BThe type of refrigerant used
  • CThe ambient temperature
  • DThe efficiency of the refrigeration components

Exam tip

Always start with the size of the refrigerated space when sizing a refrigeration system.

Why A is correct

The size of the refrigerated space is the most critical factor when sizing a refrigeration system. It determines the amount of refrigerant needed and the capacity of the system.

6 more in the bank

Answers and explanations for these are in the app.

  • A refrigeration plant designed to handle a cooling load of 150 tons requires a compressor suitable for this application. Which of the following compressor types is most suitable?
  • A refrigeration system in a manufacturing facility is suspected of having a refrigerant leak. Which of the following methods is the most effective for detecting the leak?
  • What is the main function of the condenser coil in an industrial refrigeration plant?
  • What is the primary purpose of a finned evaporator coil in a retail store refrigeration system?
  • Which method is typically used to detect refrigerant leaks in an industrial refrigeration plant?
  • Which refrigerant is commonly used in medium-temperature commercial refrigeration systems due to its high refrigeration capacity and moderate environmental impact?

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